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
BSL MP41 kit rental

Practical Lab Kit for Remote Learning

BSL Home rentals enable students to conduct hands-on physiology labs in the safety of their own home, dorm room, or any remote location while social distancing and stay-at-home orders keep them out of campus labs Complete lab solution to preserve practical lab experience!  For instructors—BSL Home makes it easy for instructors to continue running practical […]

View All
Latest News

New Citations | Respiration Analysis and More

Comparing Diaphragm Tissue Between Healthy and Ill Patients The human diaphragm is one of the primary muscles used in respiration, contracting and expanding to control breathing. To measure how much diaphragms move for critically ill patients (in an Intensive Care Unit) compared to diaphragms in a healthy subject, patients at “Papageorgiou” General Hospital in Thessaloniki, […]

BIOPAC Systems Helps STARK Industries Launch VITAL Ventilator for NASA JPL

BIOPAC’s ventilator testing equipment and expertise supports STARK Industries’ effort to manufacture, validate, and test NASA JPL’s VITAL Ventilators Goleta, California – June 16, 2020 BIOPAC Systems, Inc. announced a partnership with STARK Industries, LLC to provide ventilator validation and testing equipment for the mass production of ventilators. STARK Industries was awarded a global license […]

Read All
Request a Demonstration
Request a Demonstration