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Forensic Acoustics

Forensic Acoustics is the application of the physics and physiology of sound to issues in the law and matters of public interest.

A current well-known example of forensic acoustics is voice-print analysis. However, voice-print analysis is only a narrow aspect of forensic acoustics. Most of our work in forensics involves analysis of sound levels, sound quality, and environmental factors.

Two cases:

• The victim of an assault alleged to have been committed in an office space claimed to have called out for help during the assault. Co-workers did not corroborate that claim. BRC was retained to determine whether those in the vicinity should have been able to hear and recognize such a call.
• A collision between a car and a train at a rail crossing that was not gated killed the driver of the car. Our role at trial was to analyze whether the driver should have heard the train whistle in time to stop before colliding with the train.

Note that in the previous examples, as with voice-print analysis, conclusions must be drawn on the basis of analysis of evidence rather than on clear-cut matters of fact. This is usually the case, and it often means that the conclusions are open to question.

However, sometimes the evidence is very clear. In one well-documented case a helicopter working at low altitude over a filming location crashed, killing three actors. The video of the event was inconclusive, but the audio established that the helicopter's tail rotor sustained an impact and ceased operating before the aircraft began descending, thus ruling out pilot error.

Fortunately, most cases requiring forensic acoustics don't involve death or injury, and in many instances our work is for the purpose of promoting safety of life and health. Examples include predicting the audibility of warning devices, designing industrial noise mitigation to meet OSHA or state standards, acoustical design of schools to meet environmental and interior noise limits, and acoustical testing of walls and floor-ceiling assemblies to determine compliance with building codes or similar standards.

Expert Witness Testimony

Expert witness testimony is a key component for supporting the findings and conclusions of acoustical analyses in public hearings, providing professional opinions for noise disputes between private or commercial parties, and for peer review of acoustical documents, findings, and conclusions. A skilled expert witness provides clear explanations of often complex acoustical issues, articulates the key elements that define the issues and solutions, and supports conclusions with solid scientific research and experience.

BRC Acoustics has successfully testified in numerous land use hearings, legal proceedings, and public forums. Our expert witness experience includes acoustical issues related to the legal and environmental impacts of industrial facilities, the contribution of emergency siren audibility to vehicle accidents, the effect of low-flying military aircraft on sleep and communication in nearby residences, and a range of other varied acoustical topics.