What Is Biomedical Acoustics?

Biomedical acoustics is a field concerned with the application of acoustic phenomena to the diagnosis, monitoring, and treatment of human health conditions. It draws on principles from physical acoustics, electrical engineering, and physiology to study how sound and ultrasonic waves interact with biological tissues and systems. The field encompasses both passive listening techniques, such as auscultation and phonocardiography, and active techniques, such as diagnostic ultrasound and focused ultrasound therapy.

The discipline traces its foundations to early clinical observations that sound carries information about internal physiology. Modern biomedical acoustics integrates transducer design, signal processing, and acoustic wave theory to move far beyond the stethoscope, producing tools capable of imaging organ structure in real time, destroying tumors non-invasively, and restoring hearing through implantable devices.

Acoustic Measurements and Ultrasound Characterization

A central technical challenge in biomedical acoustics is characterizing the acoustic fields generated by medical devices precisely enough to ensure both effectiveness and patient safety. Hydrophones, devices that convert acoustic pressure into electrical signals, are the standard instrument for this task. As reviewed in a 2023 study on hydrophone measurements for biomedical ultrasound, measurements must capture peak compressional and rarefactional pressures, intensity distributions, beam geometry, and derived bioeffects indices including the Thermal Index and the Mechanical Index. These values govern regulatory submissions to agencies such as the FDA and inform the safe operating parameters of clinical devices. Since the landmark 1988 special issue on ultrasound exposimetry in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, the field has developed international standards through bodies including the IEC and NIST to keep measurement methodology aligned with advancing transducer technology.

The Auditory System

Biomedical acoustics has a long-standing and productive relationship with audiology and hearing science. The ear is itself a sophisticated acoustic transducer: it converts pressure waves into electrochemical signals through the mechanical motion of the tympanic membrane, the ossicular chain, and the basilar membrane of the cochlea. Engineering interventions in hearing rely on understanding each stage of this acoustic-to-neural pathway. Acoustic sensing devices, including implantable microphones and piezoelectric accelerometers, are integrated into cochlear implant systems and middle-ear implants to bypass damaged structures. As documented in research on sensing devices for detecting acoustic signals in healthcare, wearable and implantable acoustic sensors now achieve high-fidelity detection of physiological sounds across a range of clinical contexts. Research groups such as the Biomedical Acoustics program at the University of Rochester focus specifically on measuring and personalizing ear canal acoustics to improve hearing-aid fitting and implant performance.

Therapeutic and Diagnostic Applications

Beyond imaging and hearing, biomedical acoustics supports a broad portfolio of therapeutic interventions. High-intensity focused ultrasound (HIFU) deposits acoustic energy with sufficient spatial precision to ablate tumors, dissolve kidney stones by lithotripsy, and modulate neural circuits non-invasively. Diagnostic applications extend from conventional B-mode imaging of fetal anatomy and abdominal organs to elastography, which maps the mechanical stiffness of tissue as a marker of disease, and photoacoustic imaging, which couples pulsed laser excitation with ultrasound detection to achieve optical contrast at acoustic depths.

Applications

Biomedical acoustics has applications in a wide range of disciplines, including:

• Obstetric and fetal medicine, through real-time ultrasound imaging
• Oncology, through HIFU tumor ablation and photoacoustic tumor imaging
• Cardiology, through phonocardiography and intracardiac echocardiography
• Audiology and otolaryngology, through cochlear implants and hearing-aid acoustics
• Neuroscience, through transcranial focused ultrasound neuromodulation