How to solve howling?1. Check the size of the earplugs when wearing them . Choose the earbuds that best fit your ear. Insert the earplug firmly into the ear hole to ensure there is no gap.2. Before wearing, please turn off the power and reduce the volume.3. After wearing, turn on the power, gradually increase the volume from the minimum, and adjust.Why choose our Hearing aids?1.This device is designed for seniors or adults.2.Selected superior chip with fine sound quality and stable transmission performance.3.Its clearly sound quality and big power can be used for senior or adults.4.Easy-to-wear design, conform to your ear shape, stable wearing and can ensures the comfort.5.Full digital circuitry, low power consumption, adaptive noise reduction, and can prevents howling.6.Soft silica gel material, does not harm to your ear, and also ensure wearing stability and lasting.7.Directly inserted into the recharging base for convenient USB recharging, and the indicator light can direct display the recharging status.8.One-key operation for volume, on/off, and program selection.Specifications:Max sound out put:1293dBSound gain:>= 40dB5dBTotal harmonic wave distortion: