the impact of headphones and earphones on hearing

THE IMPACT OF HEADPHONES AND EARPHONES
ON HEARING OF USERS
Pavel Obdržálek, Martin Rod
Gymnázium Christiana Dopplera, Praha, ÈR
Assumption
Long term incorrect earphone usage can cause permanent hearing damage.
(1)
Theory
1.Insertion of the earphones into the ear canal changes excitation conditions.
2.Transfer function of the ear canal changes: resonance peaks are shifted.
3.Subjective volume level settings causes overexcitation and consecutively permanent damage of hair cells.
Measurement
1.Subjective measurement methods on humans (audiograms - audibility threshold and
subjective changes caused by devices)
2.Objective measurement methods using artificial head (frequency analysis)
(All tests performed with headphones as well as earphones)
Tested devices
Headphones: Bayer, k.55, Koss MV1(1), Koss UR-15C, Philips SHP1900(2), Sennheiser
Earphones: Koss earbuds, Creative MX(3), Nokia, noname
(1)
selected as reference
(2) (3)
selected for testing
(2)
(3)
Fig. 1: Audiogram - subjective measurement
Fig. 2: Frequency characteristics of reference headphones
Fig. 3: Frequency characteristics of tested headphones
Fig. 4: Frequency characteristics of tested earphones
Results
1. Headphones: Resonance shift is negligible.
2. Earphones: Frequency response between subjective
and objective measurements correlates except of the
600-3000 Hz range where the measured difference
increased up to almost 25 dB.
Wrong interpretation of the earphones
characteristics and their misuse
may lead to the damage of ear apparatus
and cause partial hearing loss.
Fig. 5: Subjective and objective measurement of headphones and earphones in comparison to reference headphones
Project supervisor: Ing. František Rund Ph.D. (FEE CTU Prague)
This work was part of the “Cesta k vìdì” (Route to Science) project supported by OPPA / ESF