In-ear headphones are a daily essential for millions, but ensuring top-tier sound quality is more complex than it seems. Beyond frequency response, ear canal geometry significantly impacts how sound is measured and experienced. Insights from the GRAS Sound & Vibration whitepaper, The Impact of Ear Canal Geometry on In-Ear Headphone Testing, reveal how ear simulators and ear canal variations affect audio quality.
Why Ear Canal Geometry Matters
Accurate headphone testing requires replicating the human ear. Ear simulators, such as the 60318-4 IEC standard Ear Simulator (100 Hz – 10 kHz), the GRAS “711” High-Frequency Ear Simulator (100 Hz – 20 kHz), and the ITU-T recommended Type 4.3 Ear Simulator (20 Hz – 20 kHz), assess sound quality across the audible spectrum. However, their accuracy depends on mimicking ear canal shape, size, and behaviour.
While some simulators assume an “average” ear canal, real-world tests show factors like insertion depth, canal volume, and leakage significantly impact results. The pressure field in a semi- or fully enclosed ear simulator depends on how well the device fits—a key factor for both accurate testing and user experience.
Testing Challenges
The GRAS whitepaper features acoustics experts such as Brian Johansen, Rasmussen, and Morten H. Pedersen, and it highlights how small changes in ear canal geometry, such as shape and volume, influence test results. While canal volume and headphone placement matter, canal shape (circular vs. oval) is less critical. These insights underscore the complexity of achieving consistent, realistic headphone testing.
Learn More
Curious about how ear canal geometry affects headphone design and testing? The whitepaper explores transfer impedance, ear simulator models, and real-world testing challenges.
Stay ahead in the industry—visit or sign up here .
