BIOPAC® Systems, Inc. Logo

Audio recording synchronization

When performing some experiments, it may be desirable to link a recorded audio file to a recorded data file.  For instance, a subject may be speaking, listening to voice commands, or listening to sounds played by a computer's speakers as physiological data are acquired. 
 
Audio can be synchronized with other data types by connecting a sound signal directly to the MP150 system.  To do this, the sound signal must be relatively large, such as the line level signals used to drive a set of speakers.  Microphone levels would generally be too low and have to be amplified.  The audio out from the sound card of a computer would generally suffice.  However, this signal would typically be stereo.  Inputs to the MP150 system have to be mono.  A stereo to dual mono Y-cable could be used to bring the sound out of a computer's soundcard, and then one or both channels could be brought into the MP150 system via CBL100.
 
If none of the measures of the human subject involve direct electrical connections to that subject — that is, if no ECG, EMG, EEG, etc. signal is recorded from the subject, then the CBL100 can be connected directly to the front of the UIM100C.  If electrophysiological recordings from human subjects are part of the experiment, then the output from the sound card must go through an INISO and HLT100C.   For more information about the potential safety hazard involved here, please see the Knowledge Base entry on galvanic isolation.
 
Let us assume the audio is plugged into channel 5 of the UIM100C (or the HLT100C). Make sure this channel is not used by another amplifier. Enable channel 5 in the Acqknowledge software to acquire the sound. The higher the sample rate the better the sound will be captured (for example, a 40 000Hz sample rate would capture the entire range of human hearing.) But even at sample rates lower than 1000 Hz it is possible to pick up the sound as noise which will serve fine as a marker.
 
It is probably best to use a loud sound as a marker at the beginning of the experiment so that it can be easily recognized in the Acqknowledge recording and in the audio recording. After the data are acquired, it is possible (only for Windows computers) to bind the sound recording (in a .wav file format) to the Acqknowledge recording in the same way that video can be bound to an Acqknowledge recording. Consult the section on Playback under the Video chapter in the Acqknowledge software guide for further details.
 
Page last modified 22Dec2014

Associated Applications

Spotlight On
BIOPAC training

T4 Human Physiology Conference

Register Today! T4: Tools, Trends, Techniques, and Technology Monday, July 24, 2017 – Wednesday, July 26, 2017 Join BIOPAC for three days of hands-on, small-group human physiology workshops, presented by renowned experts, on the beautiful University of California at Santa Barbara campus in Santa Barbara, California, USA. Who should attend Anyone who records and analyzes […]

View All
Latest News

Mobita Advances Prestimulus EEG Research

The Mobita 32-Channel EEG recording system was used in research examining if physiological data can be used to predict truly random events that correspond to perceptual stimuli. Baumgart, et al. from the University of California Santa Barbara utilized a quantum random number generator (qRNG) to choose from three randomized conditions: light, sound, and no stimulus. […]

News Citations—Respiration and Cardiovascular Activity

BIOPAC provides software and hardware that allow for research teams to record and analyze respiration activity in physiological experimentation. Here are a few notable studies in monitoring respiration and cardiovascular activity. The coupling between peripheral microcirculation and slow breathing: The purpose of this study was to investigate the coupling of breathing movements and microcirculatory blood […]

Read All
Request a Demonstration
Request a Demonstration