Effects of an Active Noise Control Technology Applied to Earphones on Preferred Listening Levels in Noisy Environments

Abstract

Background and objectives: The harmful effects of frequent exposure to loud sounds through portable music players (PMPs) in combination with earphones have been suggested to result in a high prevalence of recreational noise-induced hearing loss among children, adolescents, and young adults. The present study aimed to evaluate the effects of an active noise control technology applied to earphones on the preferred listening levels (PLLs) while listening to music in the presence of background noise.

Subjects and methods: Twenty-three adults between 20 and 40 years with normal hearing were recruited for this study. PLLs for listening to pop-rock and classical music were measured in the participants' ear canal with a commercially available PMP for four earphone/headphone configurations in quiet and noisy conditions. Ear canal insertion loss was measured in open ear conditions as well as earphone/headphone conditions.

Results: The average PLL while using earphones and headphones exceeded 85 dBA corresponding to the sound level to induce hearing damage, but in the case of canal earphones with noise cancelling (NC), it was below 75 dBA, corresponding to potentially harmful levels. The background subway noise significantly increased the PLL measured in quiet conditions using any four earphone/headphone types except canal earphones with NC. Canal earphones with NC showed the lowest PLLs compared with participants' average PLLs using the other three earphone/headphone types.

Conclusions: To minimize recreational noise exposure at the risk of PMP use, the use of earphones with NC is recommended in noisy environments.

Keywords: Background noise; Canal earphones; Noise cancellation; Portable music player; Referred listening level.

Fig. 1.

Diagram of experimental settings and equipment.

Fig. 2.

Four types of earphone/headphone used in the study. CP, canal earphones; NC, noise cancelling.

Fig. 3.

The average preferred listening levels of (A) pop-rock music and (B) classical music for earbuds (n=23), headphone (n=23), canal earphones (n=23), and CP with NC (n=10) in quiet and noisy conditions. Each value in headphone, canal earphones, and CP with NC is statistically compared with that in earbuds. Open symbols: quiet environment; closed symbols: noise environment; vertical bars: standard deviation. ^*p<0.01. CP, canal earphones; NC, noise cancelling.

Fig. 4.

The increases in preferred listening levels calculated for earbuds (n=23), headphone (n=23), canal earphones (n=23), and CP with NC (n=10) by subtracting the preferred listening levels selected in a quiet condition from that selected in a noisy one, when listening to (A) pop-rock music and (B) classical music. ^*p<0.05; ^†p<0.01. CP, canal earphones; NC, noise cancelling.

Fig. 5.

Ear canal insertion loss across the frequency calculated as the difference between the noise in the earbuds (n=23), headphone (n=23), canal earphones (n=23), and CP with NC (n=10) condition and open ear condition. The values are expressed as means+standard deviation. CP, canal earphones; NC, noise cancelling.

Fig. 6.

Comparison of ear canal insertion loss among earbuds (n=23), headphone (n=23), canal earphones (n=23), and CP with NC (n=10) at (A) 250 Hz, (B) 500 Hz, (C) 1 kHz, (D) 2 kHz, (E) 4 kHz, and (F) 8 kHz. ^*p<0.05; ^†p<0.01. CP, canal earphones; NC, noise cancelling.

Fig. 7.

Relationship between the increase in preferred listening levels and the ear canal insertion loss. A: pop-rock music; B: classical music. CP, canal earphones; NC, noise cancelling.