The Korea Consumer Agency (KCA) tested the quality and labeling of 12 voice amplifier products on the market and found significant differences among products in key performance areas including bandwidth, amplification, distortion rate and noise level, according to results released Wednesday. Some products also showed discrepancies between the performance specifications listed in product manuals or descriptions and actual measured values, requiring improvement.
A voice amplifier is a device that amplifies speech and sound, similar to a hearing aid. However, hearing aids are classified as medical devices, while voice amplifiers are classified as non-medical devices. In particular, while hearing aids can cost up to 5 million won ($3,600), the most expensive voice amplifiers are available for around 500,000 won, drawing growing consumer interest.
The KCA measured bandwidth — how wide a range of frequencies a device can amplify. The lower frequency limit ranged from 100 to 318 hertz (Hz) across products, while the upper frequency limit ranged from 3,500 to 8,050 Hz. The Dampf (G16) product had a relatively wide bandwidth of 132 to 8,050 Hz. A wider bandwidth allows users to receive richer sound information from low to high tones.
Amplification performance was measured in two categories: acoustic gain and output sound pressure level. In the acoustic gain test, which measures how much a device amplifies sound at 50 decibels (dB) — similar to normal speech volume — the Liner (Nova) product showed the highest amplification with a maximum of 60.8 dB and an average of 35.0 dB. The MGTech (Hwakcheonggi) product was relatively low with a maximum of 9.8 dB and an average of 2.5 dB.
For output sound pressure level, which measures the loudest sound a device can produce, maximum output ranged from 100.5 to 123.7 dB and average output ranged from 90.0 to 116.1 dB. The Cheonga (TS-22) product had the highest maximum output at 123.7 dB, while the Cuo (LT2303) product had the highest average output at 116.1 dB.
The distortion rate — the ratio of noise to the original sound — ranged from 0.1% to 4.7% across products. The Cheonga (TS-22) and Liner (Nova) products showed the least distortion at 0.1%. The noise level generated by the devices themselves ranged from 3.4 to 43.2 dB, with the Liner (Nova) product showing the lowest noise at 3.4 dB.
Additionally, the KCA tested actual performance against stated product specifications and found discrepancies in some products.
Maximum acoustic gain differed by up to 30.2 dB and average acoustic gain by up to 13 dB from stated values. Eight of the 12 tested products showed differences between stated and measured values in key test categories. Five products lacked warning labels stating that misuse or overuse could negatively affect hearing. After the KCA recommended labeling improvements, all sellers of the affected products accepted the recommendations, correcting performance specifications and adding warning labels.
All tested products functioned properly in their core sound amplification capability. "Unlike hearing aids, voice amplifiers cannot be tried on before purchase, so consumers should check ear tip sizes and other fit factors to gauge personal comfort," the KCA said. "Products differ in features such as Bluetooth connectivity and frequency-specific calibration through dedicated apps, so it is important to choose based on individual usage characteristics and environment."