Audio Recording Techniques & Equipment Saami Winter School Feb 10 Bodø, Norway David Nathan Endangered Languages Archive Hans Rausing Endangered Languages Project SOAS, University of London
Topics - session 1 • Questions • Audio workflow • Evaluating recordings • Perception and psychacoustics • Microphones • Connections • Recorders • Carriers
Questions • You buy a recorder for $x. A matching microphone would cost: (a) 3x (b) 0.75x (c) 0.3x (d) 0.1x (e) none of these - cost is irrelevant
Big questions • What are we actually recording? • What is it for? • What is the role of audio in language documentation?
What is audio? • Audio is not data • real world • record phenomena • represent phenomena • derive data • Audio is a resource • making it is both art and science • a critical and ethical responsibility • strongest relationship to communities • it’s not necessary to record everything, but it is neceessary to record well
Audio workflow Before you go who/what/where /why/how do you want to record? contact people audio training equipment & budget assemble, test, practise
Audio workflow On site, before recording transport safely check environment, situations, permissions local training & collaboration make test recordings
Audio workflow Sessions monitor record! monitor! collect metadata label check quality
Audio workflow After sessions label check quality backup add information (transcriptions, annotations, metadata etc)
Audio workflow Later add information (transcriptions, annotations, metadata etc) send samples to archive ... package and send to archive
Evaluating recordings • signal • noise • signal to noise ratio • listenability (eg comfort, consistency) • fit for purpose
Evaluating recordings • audio professionals use the human ear as evaluator of audio quality and value, while many linguists mistakenly look to formats, wave-forms, analyses etc 44.1 KHz, 24 bit
Signal - what you want • content • contextual and spatial information • fidelity • comfortable to listen to
Noise - what you don’t want • from environment: • near: people, animals, activities • far: traffic, generators, planes • machines: refrigerators, fans, computers • not hearable: mobile phones, electrical interference • acoustic: reflections/resonance
Noise - what you don’t want • generated by event (unwanted) • shuffling papers, clothes • table banging • backchannel from interviewer • equipment handling, especially microphones and cables
Avoiding handling noise • use stands and cradles etc
Noise - what you don’t want • generated by equipment • wrong input levels • circuity noise (cheap or incompatible) • compression loss or distortion • ALC/AGC effects (pumping) • video camera motors
Evaluating environment/situation external environment • access • electricity • external noise sources
External noise sources • see also General principles
Close-up noise sources • machines
Dealing with noise sources • be prepared and aware • seek collaboration • monitor • use or modify room acoustics • location • direction • surfaces • reflection • absorption • isolation
Room acoustics • location • away from doors, windows, traffic areas • direction • face away from noise sources • surfaces • avoid hard smooth surfaces • reflection • avoid parallel surfaces • absorption • choose or create soft or rough surfaces • isolation • find an ‘’airtight’’ place
Audio perception/psychoacoustics • audio information is diverse • a human listener has: • location and orientation in physical world • two ears - which are incredibly sensitive • a brain/mind • the mind merges and selects from various sources of audio information • listening is actually a “hallucination” • so what should we record? • typical recording methods are unscientific!
Psychoacoustics and recording • microphones are notlike camera lenses • they don’t have “edges” • don't distinguish wanted and unwanted info • the recording process removes some information
Implications for recording • you need to set goals, plan and manage recording • goals • equipment • sources • environment • settings • example: recording spatial information • why is this important?
“Sound stage” • spatial information is an essential part of audio • we are amazingly attuned to it • we should record in stereo
“Sound stage” • ... or in ORTF (binaural)
Microphones and audio quality • microphones are the greatest determinant of audio recording quality • selection of appropriate microphone(s) for the task • placement and handling of the microphone(s)
Microphones in the digital era • microphones in the digital era • recorder quality has increased but prices decreased • microphones have become comparatively more expensive • why? microphones are analogue devices!
Microphone types • principle: dynamic vs condenser • directionality: omni, cardoid, and shotgun • spatiality: mono, stereo, binaural
Microphone physical principles • dynamic • generate signal from sound pressure • more robust, less accurate • used for musical and live performance • condenser • more fragile, sensitive and accurate • need power source - battery or phantom power • in general, use condenser microphones for language documentation
Omni • lavalier or tie-clip microphones are typically omni-directional
Microphone directionality - cardioid cardioid
Cardioid • many “standard” handheld microphones are cardioid units
Microphone directionality - shotgun directional/shotgun/hypercardioid
Shotgun • shotguns are good for quiet sources, in some noisy environments, and for video work
Stereo microphones • spatial information is an essential part of audio
110° 17cm Simulating ORTF with 2 cardioids
Microphones - quality • generally, you get what you pay for • each model has its own subjective colour • decent microphones for language documentation fieldwork cost from £120 to £300
Reputable makers - include • AKG • Audio Technica • Beyerdynamic • Røde • Sennheiser • Shure • Sony
Microphone usage principles • where should the microphone be? • in general, about 20cm from the speaker’s mouth • the inverse square law is your friend ...