Sounds Good

1. Sounds Good The art of recording sound for video: selecting the right microphone, and where to put it! This presentation has links to websites and is intended for personal viewing on a computer. Compiled by Pete Heaven, January 2018 1

2. Introduction Choosing a microphone is one thing; knowing how to use it is very much another! My own background is 35 years building, installing and operating Public Address systems, and others will be able to offer advice based on broadcasting etc. Sound is often a poor cousin of vision; cameras and their various attachments can cost an arm and a leg, three fingers and a toe, and then you need a mortgage for a decent tripod and pan-and-tilt head, so paying a few hundred for a microphone (and possibly a mixer, with or without an on-board recorder) is often a step too far when the money’s run out. But sound is so important. It’s not just speech, it’s not just spot effects and music, and it doesn’t just complement the image; it’s also a powerful subconscious influence on our understanding of what we see, and prepares us - whether we realise it or not - for what is happening, or about to happen, on the screen. There’s a lot of information here with links to appropriate websites, and much is provided just for reference. I hope that at least some of it will be of interest, maybe help you to solve a problem, understand more of the technology, and - ultimately - spend wisely. Pete 2

3. Contents Slide No. 4 Things to consider 5 Glossary of Terms 6 Frequency Ranges - Audible 7 Frequency Ranges of Human Voices and musical instruments 10 Types of Microphone, Phantom power and others 14 Radio Microphones, Legal Frequency Ranges 18 Microphone supports 20 Unwanted Noise 21 Microphone Placement 22 Microphone Accessories 24 Acoustic Cameras 26 Popular Makes of Microphone 27 Likely scenarios, suggested kit 30 Recording Narration, voice-overs 31 Which microphone should you choose? 36 Studio Sound Treatment and Microphone Set-up 40 Setting up Recording Levels, Zero dB 47 Recording on Location and Outdoors 49 How the ‘Gun Microphone’ works 50 Diagrams of Sound Reflections to consider 57 Conclusion 3

4. With images, the lens will select exactly what you’re including in the shot. Sound is different! it’s very difficult to isolate what you want to record. First, you need to establish the nature of the sound you wish to record; what is the likely frequency range? Church organ, human voice, mouse, bird, waterfall... You need to consider the likely distance between the mic and the sound source. You need to consider the sound perspective; close or distant, to match the image. You need to consider whether you want to record something that is quiet or loud. Will you be indoors or outdoors? You need to consider the ambient/background noise level and (e.g. room) acoustics. You may need to consider the weather; high humidity may be a problem for condenser mics. Wind noise may be a problem - you may need a wind muff/gag. You need to consider whether you are recording a single source, such as an artist, or multiple sources such as a choir. Will you be using a built-in mic on the camera, or an external mic; maybe hand-held, on the artist, or on a boom? Perhaps a radio mic? Or even a personal recorder? You need to consider whether the mic will be in shot, whether on view or concealed. If you need to use more than one mic, you will probably need a mixer. 4

5. Glossary of Terms used in the following slides Foley – ‘manufactured’ sounds to emulate real life or as effects; e.g. using coconut shells for the sound of horse’s hooves, a vacuum cleaner for a jet engine, etc. Fricative – a continuant consonant produced by partial occlusion of the airstream, such as ‘f’ or ‘z’ Fundamental frequency – the component of lowest frequency in a complex vibration. Harmonic – an oscillation that has a frequency that is an integral multiple of a Fundamental frequency (double, triple, etc.). The Fundamental frequency is also the ‘1st Harmonic’. See: https://en.wikipedia.org/wiki/Harmonic Labial – a speech sound such as the English ‘p’ or ‘m’, whose articulation involves movement or use of the lips. Plosive consonants – typically ‘b’, ‘p’ Presence – when raised in level, mid range frequencies of the human voice have the ability to bring an artist ‘forward’ of other sounds to make them seem almost as if they are present in the room, adding a perceived depth to the sound. Sibilance – typically ‘s’ S/N ratio – Signal to Noise ratio 5

6. Frequency Ranges - Audible. (Source: https://en.wikipedia.org/wiki/Audio_frequency) I’ve included these for interest; no need to be paranoid! The generally accepted standard range of audible frequencies is 20 to 20,000 Hz although the range of frequencies individuals hear is greatly influenced by environmental factors. Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. Frequencies above 20,000 Hz (referred to as ‘Ultrasound’) can sometimes be sensed by young people. High frequencies are the first to be affected by hearing loss due to age and/or prolonged exposure to very loud noises. Microphone literature will almost certainly show frequency response and polar sensitivity diagrams. Some microphones will have a low-cut filter switch (usually 80-160 Hz), which may reduce unwanted low frequency sound such as wind noise. 6

7. Frequency Ranges of Human Voices – Hz Voices of soloists: BassBaritoneTenorAltoMezzo-Soprano Soprano 70 - 7,500 100 - 7,500 120 - 7,500 180 - 8,500 220 - 9,500260 - 10,500 These figures have been judged from a Sennheiser bar chart and are approximate! The speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz. Note that presence can seem to ‘bring a voice forward’, or towards you. This is generally achieved by boosting the upper mid-frequencies (4-6 kHz) of the voice using a graphic equaliser or software, and can be very effective. Lots more info here: http://www.proav.de/index.html?http&&&www.proav.de/audio/speech-level.html https://en.wikipedia.org/wiki/Voice_frequency http://www.audio-issues.com/music-mixing/5-need-to-know-frequency-areas-of-the-vocal 7

8. Frequency Ranges of Musical Instruments - Hz Piano Organ Banjo Guitar Triangle Cymbals Xylophone Drum Piccolo Flute Baritone Saxophone Clarinet Bassoon Double Bassoon Trumpet Trombone Bass Tuba Violin Double bass 32 - 7,000 16 - 10,000 70 - 1,350 70 - 1,350 2500 - 15,000 280 - 14,000 125 - 12,000 70 - 15,000 550 - 14,000 250 - 12,000 120 - 1,350 140 - 10,000 60 - 9,000 30 - 7,000 140 - 8,500 60 - 7,000 40 - 3,500 160 - 12,000 32 - 4,500 These figures have been judged from a Sennheiser bar chart and are approximate! A good visual guide can be found at: http://www.donbarbersound.com/media/libFrequencyRangeofInstrumentsAndVocals.pdf (reproduced on next slide) See also: http://www.zytrax.com/tech/audio/audio.html ...where you will find lots more info on the frequency ranges of instruments and the human singing voice, and oodles of other stuff too! Worth a look. 8

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10. There are many types of microphone. Here’s a few of the common ones: Crystal. Usually extremely cheap and supplied with toys. Ribbon. Was popular for a time (e.g. ‘Reslo’) but now specialised; can be fragile. Dynamic. Unpowered but robust; low output signal. Widely used. Condenser/capacitor. Now commonplace, requires external power, or from a battery. Radio mic. Any and all types of mic, ‘connected’ via a radio link. Pickup patterns: Omni (anything and everything around it!). Cardioid (‘heart’ shaped - less sensitive to sound from the rear). Super/Hypercardioid (‘Gun’ or ‘Rifle’ mic; more directional, but also sensitive to rear). Figure-of-eight (typical of ribbon mics; sensitive to front and back, but not sides). Mono, Stereo (co-incident pair, MS (mid-side) stereo. Binaural microphones emulate natural hearing and may be mounted on a dummy head; listen on headphones). Surround (high tech and expensive multi-channel). Connection: Balanced or Unbalanced (unbalanced can be susceptible to inductive pickup). 3.5mm Tip/Ring/Sleeve (TRS) - widely used; could be a balanced or stereo connection. ¼” Jack TRS – usually for on-stage amplifiers. Amphenol – 4 pin with a threaded collar to secure. Now rare. XLR – industry standard 3-pin latching connector. Now universal! USB – digital output (some mics and some mixers provide a digital output). 10

11. Connection - Powering your microphone - Phantom power and others Dynamic Dynamic microphones are not supplied with power but generate a voltage from the changes in air pressure due to the sound waves. This voltage is very low, usually just a few millivolts, and equipment with a good clean high-gain pre-amp is essential. Plug-in power (PiP) A 3 to 5 volt supply provided at the microphone socket of some consumer equipment, usually for electretmicophones (see next slide for more info). T power A previous method of supplying power, and although still used is now generally superseded by Phantom powering. Inline XLR adaptors are available to run T-power microphones from P48 sockets, allowing older (possibly second-hand) equipment to match modern cameras and mixers. See https://www.canford.co.uk/PHANTOM-TO-T-POWER-CONVERTER Phantom powering 48v (aka P48), 24v, 12v, but 48v is now commonly used for condenser microphones. A phantom circuit has direct current applied equally (at the same polarity) through the two signal lines of a balanced audio connector (e.g. both pins 2 and 3 of an XLR connector). The supply voltage is referenced to the ground pin (pin 1 of an XLR). See https://en.wikipedia.org/wiki/Phantom_power for a full explanation. 11

12. Connection - Powering your microphone - Phantom Vs Plug-in Power Source: http://www.shure.com/americas/support/find-an-answer/difference-between-bias-plug-in-power-and-phantom-power (scroll down) Phantom power is used to power up the electronic preamp (also called an impedance converter) for professional condenser microphones. It is 11 to 52 volts of dc power that rides on the same wires as the balanced audio signal. Plug-in power is typically 5 volts of dc used to power up the JFET of inexpensive condenser microphones. The voltage can be on a separate conductor from the audio or ride on the same conductor as the audio. Using an isolation transformer like the Shure A96F will block the "plug-in power", properly known as "bias". See: http://www.shure.com/americas/products/accessories/microphones/microphone-problem-solvers/a96f-camcorder-interface (Continued...) Plug-in power mic socket on Panasonic SJ-MR100 MiniDisc recorder (left socket) 12

13. The Shure A96F line matching transformer connects microphones with an XLR-type connector to the 3.5 mm inputs found on camcorders and other recording devices which may have Plug-in power. It increases the signal level from the microphone, provides a balanced input, and prevents distortion due to the DC bias voltage sometimes found in camcorder, MiniDisc, etc. microphone inputs. Microphone input specification (Just FYI - you’re unlikely to have a problem) Source: http://www.shure.com/americas/support/find-an-answer/condenser-mic-for-minidisc-recorder-w-plug-in-power Typically called "Input Impedance" or "Actual Input Impedance", this specification is important as it will determine the proper impedance range of the chosen microphone. This specification will be given in ohms. Contrary to popular audio mythology, the impedance of a microphone does not need to match the input impedance of your device. Multiple impedances are available depending on the make and model. If you select a microphone whose impedance is lower than or equal to your device's input impedance, the microphone will work if it provides the proper signal level.If you select a microphone whose impedance is greater than your device's input impedance, the microphone will not deliver its full signal level to your device and the audio will be noisy and low in level. 13

14. Radio mics. These not only provide freedom from the tether of a cable but also from earth loops, maybe impedence matching, possibly a mis-match of dissimilar connectors, and do not cast a problematic shadow from studio lighting which can happen with a microphone on a stand or boom. For occasional (and professional) use, buy equipment that uses removable batteries. Built-in re-chargeables don’t like intermittent use when left idle for long periods, and take a significant time to recharge - not a good situation when on location! A fresh replacement battery offers a full charge immediately with no waiting. Note that rechargeables may not reliably report their state of charge. Radio technology: Analogue, Digital, Bluetooth; the next two slides show legal frequencies. Beware of old second-hand equipment! Note that digital technologies (including Bluetooth) use analogue-to-digital convertors at the transmitter, and digital-to-analogue convertors at the receiver. This can result in a very small out-of-sync delay (or ‘latency’) which may be obvious when a take is viewed. VHF, UHF. These transmit a signal which may be received by any number of receivers within range, allowing multiple cameras to record the same live sound. Bluetooth has about 10M range between a ‘paired’ TX and a single RX. Bluetooth adaptors such as those from TaoTronics provide a stereo (or dual mono) link at line level input/output which is OK for headphones, but mics will generate way too small an input signal. It might be worth a try, possibly with a mic pre-amp or input via a small recorder. When editing you would need to slip the audio on the timeline to adjust for latency. 14

15. The tiny TaoTronics Bluetooth device shown with a pair of JVC Bluetooth headphones; this device can be switched to transmit (TX) or receive (RX). It should be possible to transmit wirelessly from a camera’s headphone socket to headphones such as these when filming. (https://www.taotronics.com/taotronics-tt-ba07-bluetooth-4.1-transmitter-receiver-aptX.html ) Also useful when watching TV late at night! 15

16. Legal frequency ranges for Radio Mics as at January 2017 Source: http://www.canford.co.uk/Technical/Article/UKLegalRadioMicFrequencies Licence exempt frequencies – No licence required These frequencies are available throughout the UK, indoors or outdoors, without a licence. There is availability at VHF and UHF and the frequencies are detailed below. All new equipment should use the following frequencies: VHF band (173.7 – 175.1 MHz)  173.8001, 74.000, 174.200, 174.400, 174.600, 174.800, 175.000  UHF band (MHz) 863 – 865 Notes Typically, up to 3 VHF frequencies can be used together;for example, 173.8, 174.2 and 175.0MHz. Typically, up to 4 UHF frequencies can be used together; for example, 863.1, 863.7, 864.1 and 864.9 MHz. Transmitter power: 10mW (Up to 50mW permitted for body-worn pack). VHF other users: Wireless microphones only.UHF other users: Wireless microphones, domestic cordless headsets and loudspeakers. (Continued...) 16

17. Older VHF equipment may continue to use the legacy frequencies: VHF band (173.7 – 175.1 MHz) 173.800, 174.100, 174.500, 174.800, 175.000Wi-Fi band (MHz) 2400 – 2483.5 Notes Manufacturers claim up to 70 frequencies can be used together. Transmitter power: 10mW. Other users: Wireless computer networks (Wi-Fi), RF Tags (RFID), Bluetooth short-range links, video links, wireless microphones, microwave ovens, movement detectors, industrial control and monitoring, wireless DMX control, digital wireless intercom. Licence exempt summary There is the potential for interference from other radio microphones. You may find that licence exempt frequencies suit your purposes; but if you want to reduce the likelihood of interference, shared or co-ordinated frequencies may be a better option. Regardless of whether you use licence exempt or licensed radio microphone frequencies, multiple radio microphones used at the same location can interact and interfere with each other. This is known as intermodulation. To avoid these problems take particular care which frequencies you use together. This document gives only brief details of the frequencies available for radio microphones and the licence fees that apply. Further information can be found on the Ofcom website. 17

18. Having chosen your preferred microphone, how will it be physically supported? Unless you’re using a mic built-into the camera, an external mic may be: Head mounted (e.g. presenter mic, possibly with headphones). Lavalier - Historically a hand-held mic on a cord around the neck; seldom used now. (Tie) Clip, or Lapel, onto clothing. A very small unobtrusive mic, now commonplace and often referred to as a Lavalier mic. Hand held, maybe on a long boom. Or a lip mic for noisy environments, as used by sport commentators who are often in very noisy and crowded commentary boxes. Boundary effect, e.g. sits flat on a table and picks up those sitting around it, maybe for teleconferencing or a discussion group; and perhaps useful for recording wedding speeches when a clip mic is inconvenient or impractical. But don’t bang on the table! Desk , Banquet, or Floor Stand (which may have a boom). These will usually have an open clip to receive the mic, allowing the user to remove and replace it easily, while a boom - especially when a long hand-held pole - might employ a sprung clip (like a big ‘Bulldog’ clip) to hold the mic securely. A flexible microphone holder can reduce mechanically conducted noise; see following slides. Suspended from above, as in Parliament and council chambers to pick up questions. Mounted in a Parabolic reflector (typically for recording distant wildlife). 18

19. Unwanted noise. This can come in several forms: Wind Noise is a real problem when filming outdoors. Some mics have a suppression circuit to filter it out, but most users rely on the ubiquitous Softie from Rycote (http://rycote.com/microphone-windshield-shock-mount/classic-softie ). Longer fibres tend to perform better, but this is not always an attractive solution, especially on the smaller sizes. A huge range is available to fit just about any mic, and will almost certainly be a worthwhile investment. Handling Noise. This is transmitted by conduction when holding the mic, so users should be aware that it is best to grip the body of the mic securely and try not to change their grip. Beware of rings on fingers! The cable can also induce noise from movement or handling, and some cables have a ‘quiet’ surface to minimise this effect. Some mic mounts have a flexible element, such as the ‘cat’s cradle’ shock mount variety which uses a rubber band principle to isolate the mic. Others have a moulded clip such as the ‘Lyre’, also from Rycote. It may be helpful to sit a table stand on a soft cloth (for example, a folded duster) to minimise sound conduction from the surface of the table. Electronic Noise. This can come from the circuitry of condenser mics; usually very little, especially when using the expensive varieties. These mics often use a 48v ‘phantom’ power supply from a connected camera or mixer/recorder, but some mics have a small battery, either a button type or maybe AA/AAA. Dynamic mics have a coil moving in a magnetic field to generate a signal, but can suffer from local magnetic influences - keep them well away from (e.g.) sound mixer mains power supply units. 19

20. Cable grip to minimise noise from movement Typical ‘Cat’s Cradle’ mount; the microphone is supported by an elastic thread Typical Rycote ‘Lyre’ mount; the microphone is supported by a moulded cradle 20

21. Microphone placement. Where is the best position to get the best sound? This is where experience really comes into play. There are few ‘hard-and-fast’ rules. Clip mics are often used by news and weather broadcasters, sometimes upside-down to avoid the effects of plosive consonants. They can be attached to a lapel or the edge of a garment, but try to avoid the weight of the mic and cable dragging the material into an unsightly crease. It may be possible to clip it just inside a garment to hide it, but beware of it being knocked by jewellery, or rubbed by clothing or body movement; a small Softie can minimise this effect, or the mic can be taped to the garment or body - Rycote ‘Undercovers’ and ‘Overcovers’ are recommended. Experiment with how close to the mouth is best. On-stage actors in theatres sometimes have a tiny mic taped to their face, usually with the wire down a parting and onto their forehead or maybe across a cheek, with the wire hidden by make-up. It’s only visible from the first couple of rows! Hand-held mics should be held about a hand-span from the mouth, and to avoid a popping effect it’s often best to talk across the mic rather than straight into it (it can then be held a bit closer). Hand held mics can be quite directional with the frequency range dropping-off when off-centre, so try to keep it in line with the mouth. Low-sensitivity cardioid mics are best for presentations when (typically) used on a stage with loudspeakers, as they are less susceptible to generating feedback (or ‘howl-round’); they can also be used for recording narration. A hand-held mic can be used with a boom at high or low level, but you need to be careful to keep it out of shot. A mic on the end of a long boom can be heavy, so a lightweight boom is good! And when plugging a mic into a camera, make sure any 48v switch is in the correct position. 21

22. Microphone Accessories. Apart from the Softies, a few goodies are available to address certain problems. Note that the human (speaking) voice has quite a limited frequency range, and using a mic with a very extended frequency sensitivity may not be an advantage as it might pick up unwanted low frequency sounds and noise. Pop Shield. When using mics for recording vocals, one of the problems is ‘popping’ noises on the plosive consonants like ‘p’ and ‘b’, and sibilance on ‘s’ sounds. The shield is designed from acoustically transparent material to give protection from these noises while maintaining sound quality. Usually a flat mesh screen, often round, mounted close to the mic between it and the speaker. See: http://www.maplin.co.uk/p/pop-shield-large-black-vw93b?cmpid=ppc&gclid=CKm5toyK1tECFUcQ0wodTb0BAQ) Reflection filter. This is a sound absorbent screen, often in a curved semi-circle, placed behind and around the mic to shield it from local acoustics and thus provide a cleaner signal free of colouration (especially when using a super- or hyper-cardioid mic indoors). Look for ‘Reflection filter’ on the web, but read this first: http://www.soundonsound.com/sound-advice/q-reflection-filter-worth-money Mic stands and supports. These range from small table stands to tall floor stands (which can also be used with a boom arm to reach (typically) over a performer while keeping out-of-shot). But as mentioned above, stands and booms can produce unwanted shadows from lights and these can compromise microphone placement. Remember that radio mics aren’t just for distant shots, they can be used even if the camera is very close to the speaker. 22

23. Pop Shield - reduces the effect of plosives, and protects against saliva which could eventually corrode the diaphragm. Reflection filter - reduces sound arriving from behind the microphone, to provide a cleaner signal. Best used with other sound control items. While inexpensive, these two items are often the subject of DIY projects! 23

24. You may be surprised to know that there are Acoustic Cameras, used by designers and laboratories to pinpoint the source of noise on things such as cars; for example, to find out if the noise is coming from the interaction of the tyres with the road surface, the transmission and suspension components, parts of the engine and so on. These cameras consist of multiple microphones in various arrangements, and use a form of triangulation to locate the noise and superimpose it onto an optical image. And yes, they are expensive! Very expensive. Here’s one: http://sine.ni.com/nips/cds/view/p/lang/en/nid/212553 ...and in use: http://spectrum.ieee.org/tech-talk/at-work/test-and-measurement/zero-in-on-buzz-squeak-and-rattle And for a bit of techie info: https://en.wikipedia.org/wiki/Acoustic_camera All very clever stuff! Now, where’s that annoying rattle coming from? 24

25. Acoustic Camera with about 100 microphones used at the 2017 Royal Institution Christmas Lecture, looking at a tea chest ‘double bass’! No sign of Lonnie Donegan though...

26. The newcomer to video will find the range of microphones that are available rather bewildering, so just as a starter and with no particular recommendation, here’s a few of the best known makes; these are in addition to external mics offered by the various camera manufacturers. It’s sometimes difficult to differentiate between similar models from one manufacturer, let alone comparing with other makes, so if you are trying to choose it would be wise to ask others for their advice. And don’t forget that you will need headphones to monitor the sound while recording; at least you will know if the microphone is plugged in... and switched on... Don’t laugh - it happened to us some years ago during auditions! Your name is..? Er... can anyone here lip-read? AKG Audio Technica Beyer, Bose Coles DPA Electrovoice Neumann Røde Sennheiser Shure For prices, have a look at the excellent Canford website: http://www.canford.co.uk Well-established brand, good range of hand-held mics Have a range of boundary mics among others Headphones popular with professionals Lip mics for commentators in noisy surroundings Small personal mics; very professional Less well-known to enthusiasts Some top end studio stuff! Dream on! On-camera mics and a good range of others Very popular with video applications; mics and headphones Very popular with Speakers, Presenters, pop groups, live performances 26

27. Likely scenarios, suggested kit The options available to you whether on location or in the studio - or your budget - may well limit your choice of microphone, so let’s consider a few situations and suggest the sort of sound kit you may need. Please try to keep it simple - leave the kitchen sink at home! You may need to visit several locations in one day, maybe at the top of a hill or at the end of a long walk, so a quick set-up and strike means taking the minimum - but the right - equipment. You will hopefully have recce’d the location in advance, have a good idea of what you need, and identified any likely problems. These scenarios are among those fairly typical: Narration, voice-over. Newsreader, person at an office desk. Presenter waving arms about to point to things and possibly moving closer. Interviews, vox pops. Stage productions, dance, drama. Weddings and Dinners. Travelling in a car, on a train, whatever. Recording a meeting or lecture. It seems that broadcasters have a penchant for speaking while standing under the rotating blades of a helicopter, or in some other noisy environment. Not a good idea. 27

28. Basic equipment list Apart from your camera, tripod, charged batteries and recording media, to capture good sound you really should invest in a good microphone or two, and a good pair of headphones. That’s three ‘goods’, and it’s a fact of life that ‘good’ means spending a little more money! OK, people will blame me for going upmarket, but don’t risk wasting everyone’s time spent on location by using poor sound gear. It’s a good idea to build up a ‘Sound check list’ to make sure you’ve got everything ready for a shoot. The following suggestions will cover most situations; a radio mic is expensive but can be very useful. Radio mic; body worn transmitter and camera receiver, with small clip mic and Softie. Cardioid microphone (for narration and vocals, and cheaper than a directional mic). Directional microphone and Softie (very useful, not as directional as you may think!). On-camera microphone (i.e. not the one built-in). Optional; limited use. Hand-held mic boom/pole (and a reel of adhesive tape to restrain the cable). Floor stand and boom. Table stand. Pack of AA, PP3 batteries, etc., and battery tester (always check batteries before use!). Leads and interconnects - XLR, 3.5mm, and any other. Headphones (essential). Mixer (optional; useful if using more than one mic and you only have one input). 28

29. I find these very useful; small and compact, and ideal to check AA, AAA, and 9v batteries before committing to a filming session - much better than having a flat battery during a take! These cost about £3-£5 but are seldom found in shops; try the web. A meter is far better than some testers that just have a couple of LEDs. Although the Draper Dry Cell Battery Tester 64514 (or BT1) is very similar to the Rolson Universal Battery Tester, I prefer the Rolson, which seems to have a better readout. Contacts to check 9v batteries Arm swings up to accept different battery sizes 29

30. Recording narration, voice-overs No video image to worry about, but you may well use your camcorder to record the sound so that it will match that of video takes. The artist will probably prefer to stand, and may have a music stand for their notes; or they may like to sit at a desk or table. If sitting in an armchair and reading from printed matter, dropping sheets on the floor when read, notes written on blotting paper used to be favourite as it was softer and quieter than print paper. But where do you put the mic? A clip mic will probably be perfectly serviceable and you won’t need to hide it, but it may not be as good as a hand-held type on a stand. If the artist is standing then a floor stand is the obvious choice, maybe with a boom if necessary. This allows a wide choice of mics, and if the mic doesn’t have a built-in ‘pop’ filter (like the one included with the Shure SM58) you can easily clip a pop shield to the stand or boom arm if required. If sitting at a desk or table, a table stand can be used, and to isolate the stand and mic from sound conductance from the surface of the desk or table, put a folded duster under the stand. If the artist is sitting comfortably in an arm chair, a short floor stand (probably placed to one side of the chair) and boom may be preferable. Particularly if one person uses more than one microphone type or make, check that the individual tonal responses are similar. Different microphones will differ in their timbre and characteristics, and this can become obvious if one microphone type directly follows another at a cut. 30

31. Which microphone should you choose? Because they are mounted near the mouth, clip/lavalier/lapel mics can have a high signal-to-noise (S/N) ratio, and they are sometimes available as omni or cardioid options; but clip mic aside, your choice will likely be between a cardioid or super-cardioid hand mic. A hyper-cardioid or gun/rifle mic may not be suitable in some circumstances; a look at their polar sensitivity diagrams will explain why (see next slide). You will notice from the following diagrams that the cardioid mic has a heart-shaped sensitivity, hence the name. It is sensitive to the front and sides, but not to the rear, whereas super-cardioid and hyper-cardioid types - despite much reduced pickup to the side, and improved front ‘focus’ at frequencies above about 4 kHz - are also sensitive to the rear, and it’s this feature that means that in an enclosed space such as a small room with lively acoustics they can pick up more echo and ambience and this can affect the clarity of the sound. These so-called ‘directional’ mics are well suited to outdoor recordings where there is unlikely to be a local echo component, but a reflection filter may help when used indoors with other sound control precautions. A cardioid hand mic may have a response tailored to vocals, with a low frequency boost when the speaker is very close to it (to provide an intimate sound), followed by a slight mid-frequency dip or ‘sag’ to reduce ‘muddy’ components, and then a lift for the higher frequencies to provide some presence. Close ‘micing’ is also when a pop shield may be useful; but if the speaker is more than about two feet (600mm) from the mic it’s probably ineffective and unnecessary. 31

32. Selecting the most appropriate mic for recording narration Here’s a simplified comparison of polar diagrams for cardioid and hypercardioid mics: (Source: https://www.youtube.com/watch?v=p1WOtGJk4YE video, 6’ 17”‘Mics for Rooms with Echo: Cardioid vs Hypercardioid’ by Curtis Judd) Frequencies above (say) 4 kHz are much more directional than shown here, and with a much lower rear sensitivity 32

33. These are the typical frequency response and polar diagrams for a Shure SM58 cardioid dynamic ‘vocal’ microphone. They are shown as an example of the uniform frequency sensitivity that can be achieved, even when off-axis, and this is surely a reason for the popularity of this mic. Microphones designed primarily for musical instruments would probably exhibit a different response. When recording in a studio set-up, use the best mic you’ve got; but this one will provide very good results and is very attractively priced, especially when compared with the cost of a good condenser mic. If you are considering buying one, there may be cheap copies about so buy from a known and trusted supplier. 33

34. The Shure SM 58(SM = Studio Microphone) A cardioid dynamic vocal microphone used just about everywhere, from pop groups to the international space station! The ball-shaped mesh is a pop shield;it can be unscrewed for cleaning. This mic is unpowered and has a verylow voltage output, way below that of powered condenser microphones;as a result, it may need a significant amount of amplification, but your camera’s AGC will usually cope. 34

35. Sennheiser MKE600 super-cardioid / lobar gun microphone with 48v phantom powering. It can also be powered by an internal AA battery (which lasts about 150 hours) making it ideal for use with DSLRs and consumer video cameras. 35

36. When recording sound, studios will pay a lot of attention to the space behind the speaker, which may seem a bit odd; but sound can bounce around in a room with hard floors and walls. Remember that the mic is pointing not just at the speaker, but also at the space behind the speaker. In this case, as you may have read elsewhere, some soft surfaces to the side and rear can be provided by the simple and cheap measure of hanging duvets from lighting and background stands. Having done this, it may help to use a reflection filter behind the mic as well, but these filters are not an instant cure by themselves and form part of the overall noise control strategy. It may not look pretty (unless you also have some attractive duvet covers!) but in this case - such as recording a voice-over - you are only interested in the quality of the sound, not the image. Recording narration when in vision - choice of positions for the mic. When recording a narrator who will be in vision, and considering the same set-ups as above, you will probably want to avoid showing the mic. You will also need to consider the lighting set-up, so carefully check the edges of the frame for any intrusion of the Softie/microphone, and any cable/s and stands. Check the whole frame for shadows, making sure that you leave at least a small margin for error around the frame - don’t place the unwanted items and their shadow right at the edge of the frame, but set them back a little. And if you don’t have access to an autocue, the narrator will have to remember their script! Or maybe use cue boards, held by a member of the crew. 36

37. If you’re using a hand-held mic and not a clip-on, this is likely to be mounted either above the actor, looking down, or at a low level (i.e. below the frame) looking up. These mic positions will obviously need to be out of shot, so you will need to get the mic as close as possible to the speaker without intruding into the frame. If above the actor, it will probably be mounted on a boom supported by a floor stand situated to one side; otherwise it could be on a low boom and pointing up to the speaker – it may depend on the framing of the shot and if there is physical space for the legs of the stand. A mic pointing down at 90° can receive a sound reflection from the floor, and it would be advisable to ensure you have some carpet in this area, so try to avoid it. If you are working in a normal room - possibly at home - which has lots of soft furnishings, these will help to avoid sound reflections from the floor and walls. These reflections can affect the clarity of the recording, and it’s a good idea to minimise them whenever you can. It might help to record across a corner of the room rather than straight on to a flat wall, to avoid the possibility of a major reflection. Sometimes you want it to sound like a room with room acoustics, but beware of ticking clocks, central heating, ceiling ventilation fans, chillers which may start up anytime and general building noises. The human brain usually cancels these out without you noticing, but a mic can’t do that, and these sounds will be there on the soundtrack. This is the reason for recording a few minutes of ambient sound; it can be used to cover gaps in the edited shots, or maybe when you are including a still photo etc. If it’s not there, it’s absence will immediately be noticed when shown. 37

38. More than one performer Sometimes you can get away with (e.g.) singers who stand very close to each other and share a single cardioid mic, but it’s usually a better option to use individual mics as this gives the option of balancing their voices. However, I remember an occasion at a major national event when we needed to mic a band, situated at the far end of a show jumping arena, to put out over the PA system. I was told to place a single ordinary cardioid mic on a boom just above the head of the conductor. The result was a sound so perfectly balanced that a member of the BBC OB staff (who hadn’t realised what we were doing) appreciated the quality of the sound balance and wondered what record we were playing! Here, the conductor was doing our work for us. Obviously, rather well! If you need to use radio mics, the free frequencies offer three VHF or four UHF simultaneous channels, but if you need more you will need to pay for alternative frequencies. These may be for a particular date, time and location, and will offer exclusive use of such channels; if anyone else tries to use them during this time they are acting illegally and may be open to prosecution. Look at the Ofcom website for details. Whether free or paid-for, choose your channels with care to avoid intermodulation, and before use always check that no-one else is using them! 38

39. Picture at right shows Sennheiser MKE600 mic in Rycote Lyre mount on Panasonic HDC-HS100 camera on MixPre-D mixer If you need to use more than one mic, you will probably need a mixer to monitor and balance the sound levels. I wanted a small portable mixer with just two mic inputs, runs on AA batteries, and because I was sometimes filming in a very tight space wanted one that can be mounted between the tripod and the camera. I didn’t need on-board recording, which some mixers offer, but this one offers the facility to record the sound on an external recorder as well as the camera. This is the Sound Devices MixPre-D, which ticks all the boxes. But it’s not for everyone - it’s professional kit with a price to match, and even the simple XL-CAM bracket that attaches to the top as a camera mount is expensive! Look them up at Pinknoise Systems: www.pinknoise-systems.co.uk 39

40. Recording levels In the past, analogue recordings were usually made on tape recorders. These served us well for many years, but there were problems; background noise/hiss from the tape, pre-echo and print-through caused by closely wound layers of tape, wear on the heads and oxide shedding being the most common. There could be a build up of oxide particles due to chemical reactions caused by using more than one brand of tape. Due to being mechanical devices, wow and flutter caused by slight transport speed changes along with tape stretch didn’t help... Changes due to temperature and humidity meant that the archive quality of tape wasn’t especially good, and we were advised to re-record onto a new tape every few years to save as much of the content as possible - but this obviously degraded the recording as well. Now we have digital file-based recordings. No moving parts and all that went with them, and due to the loss of tape noise we can use much lower recording levels without sacrificing quality if we need to raise the volume level at playback. So when recording normal sounds - referring to analogue VU recording levels - it’s now best to record the ‘body’ of the sound at about level 50, half the maximum, where previously we would have recorded around level 70. The playback ‘speed’ of the recording is now very accurate and stable due to accurate clocking, so a sound recording made on an external device should exactly match the recording made by the camera, especially for the usual short shots of a few minutes duration. But don’t forget to clapper the shot so you can synchronise the recordings on the timeline! 40

41. For those too young to remember (and those so old they’ve forgotten), this is what a VU scale looks like, showing the typical recording level. Venturing into the red zone is courting clipping and distortion! 41

42. Zero dB - Setting the best recording level You’ve forked out for a microphone, and might even have treated yourself to a mixer. How do you ensure that the quality of the sound is captured without undue degradation? Your camera might only have a default automatic gain control (AGC), in which case you will have to rely on it to make a good recording. But more expensive cameras will almost certainly offer a manual mode, where you can control the recording levels and possibly obtain a wider dynamic range rather than having a recording with a rather flat sound level. The calibration will be in dB (decibels - see next slide), ranging from a large negative number through zero to a moderate positive number. Zero dB is the reference level used to set up linked equipment, at a frequency of 1kHz, and this is an output offered by a switch on audio mixers. If you’re using just a microphone (i.e. no mixer), you will not have this set-up feature and will have to use the AGC or manually adjust the sound using the sound level indicator on the camera. When recording, your camera or mixer may have meters which offer VU and/or Peak Level indications. To avoid clipping and distortion when levels get too high, mixers will have a switch to limit input levels (and possibly output levels) to a preset value. You can, and probably will, input from the mixer to the camera using its AGC, and just use the mixer to control the sound balance between the inputs and limit any peaks. To minimise the possibility of picking up low-level noise from the electronics and cable, it’s best to link a mixer to a camera using the line level output/input connections (if available) rather than any provided at microphone level. 42

43. Zero dB - Setting the best recording level - Decibels The decibel (symbol: dB) is a logarithmic unit used to express the ratio of one value of a physical property to another, and may be used to express a change in value (e.g., +1 dB or -1 dB) or an absolute value. Decibels relative to full scale (dBFS) is a unit of measurement for amplitude levels in digital systems. The level of 0 dBFS is assigned to the maximum possible digital level. For example, a signal that reaches 50% of the maximum level has a level of −6 dBFS, which is 6 dB below full scale. All peak measurements smaller than the maximum are negative levels. With analogue, there was no real practical limit to the maximum signal (some references, such as ‘full scale’, go back to analogue metering. Going beyond maximum was often referred to as ‘bending the needle’, as it hit the end stop!) but with digital there is a finite maximum determined by a numeric reference, in this case 0 dB, so you need to be careful to avoid clipping when setting camera input levels. See https://en.wikipedia.org/wiki/DBFS Here’s a useful table which compares dB, dBu, dBV, PPM UK, PPM EBU and VU UK: https://www.canford.co.uk/Technical/Article/dBComparison And a graph: https://en.wikipedia.org/wiki/Line_level 43

44. Zero dB - Setting the best recording level continued A 1 kHz tone at 0 dB is the standard for alignment, produced by a mixer. When setting-up the camera: In Europe the EBU recommends -18 dBFS as an alignment level, but in America the SMPTE standard defines it as -20 dBFS. The BBC spec is -18 dBFS = PPM ‘4’ = 0 dBu. In 24 bit audio, alignment levels of -22 dBFS to -12 dBFS are the ones commonly used. When monitoring while recording try to keep peaks below 0dB. With digital recording, it’s better to go a bit too low rather than too high, and your video editing software may include a ‘normalising’ option to produce an improved overall sound level. So when setting up, switch the mixer to send 1kHz at 0dB, then try adjusting the level shown on the camera meter to -18 dB. This allows ‘headroom’ for loud passages, to avoid possible clipping and distortion - don’t rely entirely on the mixer’s limiter. See: https://www.youtube.com/watch?v=td11bn54aEo which would be typical in America, so set up to -18 dB instead of -20 dB which is suggested here. (Video, 2’ 35”) Also see: https://en.wikipedia.org/wiki/Alignment_level Bit of a dog’s breakfast, really! 44

45. This shows the mixer generating a 1kHz sine wave signal at 0 dBu (treat dBu as dB). The mixer is used to process the incoming signal before it is sent to the camera, so the scale goes beyond 0 dB to indicate any high level content that you need to consider. The LEDs on this mixer display input levels in a Peak and VU (perceived loudness) format. This is the metering on a DSLR camera. -18 dB isn’t marked, but the dB scale on the camera could be calibrated using a mixer. Note that for this camera, the ‘Rec level’ is set at a very low level. 45

46. Analog levels FYI, a wider view from https://en.wikipedia.org/wiki/DBFS dBFS is not defined for analog levels, according to standard AES-6id-2006. No single standard converts between digital and analog levels, mostly due to the differing capabilities of different equipment. The amount of oversampling also affects the conversion with values that are too low having significant error. The conversion level is chosen as the best compromise for the typical headroom and signal-to-noise levels of the equipment in question. Examples: EBU R68 is used in most European countries, specifying +18 dBu at 0 dBFS In Europe, the EBU recommend that -18 dBFS equates to the Alignment Level European & UK calibration for Post & Film is −18 dBFS = 0 VU UK broadcasters, Alignment Level is taken as 0 dBu (PPM4 or −4VU) US installations use +24 dBu for 0 dBFS American and Australian Post: −20 dBFS = 0 VU = +4 dBu The American SMPTE standard defines −20 dBFS as the Alignment Level In Japan, France and some other countries, converters may be calibrated for +22 dBu at 0 dBFS. BBC spec: −18 dBFS = PPM "4" = 0 dBu German ARD & studio PPM +6 dBu = −10 (−9) dBFS. +16 (+15)dBu = 0 dBFS. No VU. Belgium VRT: 0 dB (VRT Ref.) = +6dBu ; -9dBFS = 0 dB (VRT Ref.) ; 0dBFS = +15dBu. Got that? Like I said, dog’s breakfast! Be careful if you film for markets abroad... 46

47. Recording on location Obviously, with so many variables there is no clear answer here. If filming indoors then the previous suggestions apply, but if outdoors you will need to prepare for changes in the weather (high humidity can affect even top-end condenser microphones) and of course any possible problems with the particular location. It’s always a good idea to recce locations in advance and look for issues which may affect you (and of course make sure that you are allowed to film there - not always obvious; I believe that the Royal Parks in London used to forbid the use of tripods without special permission, but you could consider using a monopod. You may need to check the bye-laws). Nearby busy roads, aircraft flying overhead, crowds, and special events (check for local events on posters in shop windows, etc.) can all make life difficult for you, and the time of day (where is the sun?) can also be a factor. Building sites can suddenly burst into life with pneumatic drills and generators starting up without warning. And don’t forget to look for ease of access, parking, refreshment and toilet facilities, shelter in case of bad weather and permission to film if required. If you really have to film there but you can’t escape the noise, you may need to resort to recording a guide track and post-syncing the dialogue. Not easy for the performer, and you will need to record an equal duration of ambient noise to place at a low level behind the clean dialogue on the timeline. Just make sure that (if you filmed outdoors) the new dialogue has an ‘open’ sound quality and doesn’t have room acoustics, so choose a similar - but quiet - location to record it. 47

48. Recording outdoors - which microphone is best? If you’re not using a clip mic (with a Softie) then it’s likely you will favour a directional mic, maybe a ‘gun’ or ‘rifle’ type, also with a wind muff. But don’t rely too much on the ’directional’ description, as this is comparative; it’s not like using a long lens. You still need to get as close as possible to your actor or presenter to improve the S/N ratio. These mics go from short to long, and generally the longer the mic the more ‘directional’ its characteristics, and the higher the price! And suitable Softies don’t come cheap either, along with their mounts and attachments. You will notice that these mics are a long tube with slots at intervals down the side. These slots are intended to provide anti-phase signals to the mic capsule to cancel unwanted sounds from the sides and rear, leaving the desired signal prominent. Here’s a few from Sennheiser: http://en-uk.sennheiser.com/v4r/global_search?q=gun Be very careful with prices; despite any misleading illustration, they price the shotgun microphone head separately from the power module, which is extra. An example is their ME66 ‘super cardioid/lobar microphone head, suitable for K6 and K6P powering modules’ and currently £179. The K6 power module can accept a battery, for use when there is no phantom power available. It’s currently £209, so the total cost is currently £388. But you have the option of, for example, the ME64 cardioid head at £149. The power modules for the interchangeable heads are shown as ‘You might also like...’!!! No, you need one. Nice mics, shame about the website, so have a look at their MKE 600. 48

49. How the ‘gun’ mic works This web page from Sound-on-Sound magazine explains the principle: http://www.soundonsound.com/sound-advice/q-how-do-shotgun-mics-work It also contains gentle warnings about the effectivity of such equipment. For example, to quote from their website: “Shotgun mics don't work well at all in small rooms or in highly reverberant spaces, because the on- and off-axis sounds are inherently very similar. “ Another good explanation, with a bit of history, is here: https://randycoppinger.com/2012/04/05/how-a-shotgun-mic-works You should be aware of these points before parting with any money. Possibly quite a lot of money. That’s OK for professionals who can budget for it against a job, but not so good when it comes out of your own pocket! You could be in for a disappointment, so make sure you know what to expect. It may not be as ‘directional’ as you thought, as at lower frequencies the sensitivity is similar to a hand-held cardioid mic; so try a good cardioid first before committing to the cost of a gun or rifle mic. You also might like a mic boom (or ‘pole’), preferably a lightweight one. Various lengths are available, but you will have to consider mechanically isolating the mic from the boom to minimise handling noise. Wind (or tape) the mic cable around the boom to keep it quiet; or you could mount a radio mic and its transmitter on the end. 49

50. WALL PRESENTER Here’s a simple recording set-up MICROPHONE WALL 50