Estimating the Sound Pressure at the Eardrum and Ear Canal Transfer Function with In-Ear Headphones

Rivet E, Smeaton C, Kim JW, Welti T, Olive S, Baker J. Estimating the Sound Pressure at the Eardrum and Ear Canal Transfer Function with In-Ear Headphones. In: 2025 AES International Conference on Headphone Technology. Audio Engineering Society; 2025. Paper 17. Available from: https://aes.org/publications/elibrary-page/?id=22943

@inproceedings{Rivet2025_22943,
  author = {Rivet, Etienne and Smeaton, Calum and Kim, Jeong-Woo and Welti, Todd and Olive, Sean and Baker, Jeff},
  title = {{Estimating the Sound Pressure at the Eardrum and Ear Canal Transfer Function with In-Ear Headphones}},
  booktitle = {2025 AES International Conference on Headphone Technology},
  note = {Paper 17},
  year = {2025},
  month = aug,
  publisher = {Audio Engineering Society},
  url = {https://aes.org/publications/elibrary-page/?id=22943}
}

TY  - CPAPER
TI  - Estimating the Sound Pressure at the Eardrum and Ear Canal Transfer Function with In-Ear Headphones
AU  - Rivet, Etienne
AU  - Smeaton, Calum
AU  - Kim, Jeong-Woo
AU  - Welti, Todd
AU  - Olive, Sean
AU  - Baker, Jeff
T2  - 2025 AES International Conference on Headphone Technology
M1  - Paper 17
PY  - 2025
DA  - 2025/08/18
UR  - https://aes.org/publications/elibrary-page/?id=22943
PB  - Audio Engineering Society
LA  - en
AB  - When inserting an in-ear headphone (or earphone) in users ears, it is loaded by a range of ear canal geometries and eardrum impedances which interact with the output impedanc of the sound source. As a result, the ear canal transfer function between the ear tip and eardrum exhibits ear canal resonances above 1 kHz that may vary by one octave for the first resonance and around 10 dB between ears. The target responses for music reproduction and hear-through, which were originally tuned in an ear simulator, are thus altered at the users ears. We propose a new approach without making assumptions about ear canal geometry or eardrum impedance. The relationship between voltage, pressure and volume velocity of the earphone, which includes an in-ear microphone, are first characterized to turn the device into a pressure-volume velocity sensor. Then, the response of the in-ear microphone which is affected by the acoustic loading of the individual ear is used to calculate the input impedance of the ear. This ear impedance is then used to reconstruct the ear canal transfer function from the ear tip up to the users eardrum. Finally, the response at the users eardrum can be estimated knowing the pressure at the ear tip and this ear canal transfer function. Results in Type 2 and Type 4.3 artificial ears showed a high accuracy up to 9 kHz. They are compared to other estimations in human ears.
ER  -