It is caused by amplified sound from the hearing aid getting back to the micropphone and being re-amplified. Ways to avoid Whistling /noise Once the hearing aid is properly seated in your ear,the whistling will generally stop.
eBay
Rechargeable Hearing Aid Audifonos V30 ITC Invisible Earbuds Adjustable Tone Sound Amplifier In-Ear Hearing Device
Aliexpress UK
With the latest Bluetooth version, you get a greater range at faster speeds using lower power. Digital Signal Processing creates a safe experience that suppresses noise without blocking the speech signal.
eBay
New Rechargeable Digital Hearing Aid Adjustable Tone Best Sound Amplifier Portable Deaf Elderly BTE Hearing Aid
Aliexpress UK
Lightweight design In ear sound amplifier is small, hide it to the maximum extent possible in the ear canal. Ideal for most mild to moderate sound amplification. They capture missed sounds with maximum clarity, providing you with a clear and natural sound.
eBay
Super Mini Hearing Aid Ear Sound Amplifier Adjustable Tone Hearing Aids Portable Ear Hearing Amplifier for the Deaf Elderly
Aliexpress UK
Neckband Hearing Amplifier. Comfortable & Neckband. 1 Hearing aids. It maybe the most comfortable to wear and longest-lasting hearing amplifier you can buy. Everything you need to get better hearing.
eBay
Portable V-99 Body Hearing Aid for The Elderly Hearing Loss Sound Amplifier Adjustable Tone Digital Hearing Aids Recharged
Aliexpress UK
Input Noise:≤32dB. Max sound output:118±4dB. Sound gain: ≥32dB±2dB. Normal working about 35 hours.
eBay
2024 BTE Hearing Aid Ear for Deafness Sound Amplifier Adjustable Hearing Aids Portable Super Ear Hearing Amplifier for Eldely
Aliexpress UK
eBay
Mini Hearing Aids J25 Invisible Hearing Amplifier Ear Sound Amplifier Audifonos Hearing Aid batteries
Aliexpress UK
Mini portable charging case. -Fitting Range ： From Mild to Moderate (between 26-55dB hearing loss). Hearing Device 2. High signal noise ratio. -Dual Ear Usage ： YES. Hearing Aid Fitting In the Ear (ITE).
eBay
Hearing Aid Rechargeable Hearing Device ITE Ear Hearing Aids for The Elderly Audifonos Sound Amplifier for Deafness
Aliexpress UK
Hearing aids can effectively reduce noise and amplify sound. Our accessories include earplugs of different sizes. This small device allows you to wear comfortably and provide a clear sound. - [Comfortable] 360 degrees rotating connecting tube and ergonomic BTE design fit your ears.
eBay
Bluetooth Hearing Aid Audifonos Rechargeable Hearing Device Sports Appearance Digital Chips ITE Ear Hearing Aids For Elderly
Aliexpress UK