Hearing aid for telephone calls

Telephone calls often pose a significant challenge for people with hearing difficulties. Telephone amplifiers offer a practical solution by significantly improving the volume and clarity of conversations. These specialised devices enable people with hearing loss and those with age-related hearing loss to actively participate in telephone conversations again, without having to rely on expensive medical hearing aids.

Key points at a glance

• Telephone amplifiers increase the volume by 20 - 50 dB for better speech intelligibility
• Various types: inline amplifiers, portable amplifiers, hearing-aid-compatible telephones
• Suitable for people with mild to moderate hearing loss
• Compatible with landline telephones, and in some cases with hearing aids via the telephone coil
• Prices range from €30 to €300 depending on features
• No medical prescription required, available over the counter

What exactly are telephone hearing amplifiers?

How they work and technical basics

Telephone hearing amplifiers are electronic devices that are connected between the telephone and the handset or are integrated directly into special hearing-impaired telephones. Amplification is achieved through electronic circuits that pick up the incoming audio signal and increase the amplitude of the speech signals. Modern telephone amplifiers use digital signal processing, which not only increases the volume but can also reduce distracting background noise.

Most devices feature an adjustable volume control, allowing the amplification to be individually adjusted between 20 and 40 dB. This amplification corresponds to doubling or quadrupling the normal telephone volume. In addition, many models offer tone control, allowing high and low frequencies to be adjusted separately, which is particularly helpful for frequency-dependent hearing loss.

The key difference from medical hearing aids

Whilst hearing aids are medical devices that are individually adapted to the user’s hearing ability and fitted by a hearing care professional, telephone hearing amplifiers are over-the-counter consumer products. Hearing aids analyse individual hearing ability across various frequency ranges and specifically compensate for deficits. They feature complex algorithms for speech recognition and noise cancellation.

Telephone amplifiers, on the other hand, offer general amplification without individual adjustment. They are therefore primarily suitable for people with mild to moderate hearing problems who do not yet require medical treatment, or as a supplement to existing hearing aids. The advantage lies in their immediate availability without a doctor’s visit and their significantly lower cost.

Target groups and areas of application

People with hearing loss and hearing-impaired individuals

People with hearing impairments benefit particularly from telephone hearing amplifiers, as these enable a targeted improvement in speech intelligibility. Studies show that around 15 million people in Germany suffer from hearing problems, although only a fraction of them are fitted with hearing aids. For this large group, telephone amplifiers offer a low-threshold way to improve communication.

These devices are particularly useful for people with early-stage hearing loss who can still manage well in everyday life but have difficulty when making phone calls. The amplifiers help them to understand soft voices better and ensure they do not miss important information over the phone. Hearing aid users also make use of additional telephone amplifiers, as not all hearing aids are optimally adjusted for phone calls.

Older people and age-related hearing problems

Hearing naturally declines with age. Around one in three people over the age of 65 is affected by age-related hearing loss. Telephone amplifiers enable older people to continue making phone calls independently and maintain social contacts. Their ease of use, without complicated technology, makes these devices particularly senior-friendly.

Many older people are reluctant to visit a hearing care professional or purchase expensive hearing aids. Telephone amplifiers offer a straightforward alternative for the specific needs of telephone use. The devices can be installed and operated without any prior technical knowledge, which increases their acceptance among this target group.

Different types of telephone amplifiers

Stationary inline amplifiers for landline telephones

Inline amplifiers are connected directly between the telephone and the handset. These compact devices are about the size of a matchbox and are simply plugged into the existing telephone line. Installation requires no tools: the handset is disconnected from the telephone, the amplifier is plugged in between, and the device is ready for use.

This type of amplifier is suitable exclusively for corded landline telephones with a detachable handset. The amplification gain is typically between 20 and 35 dB, although high-quality models such as the Humantechnik PL-51 can even reach up to 40 dB. Power is usually supplied via batteries or a mains adapter, meaning no complex cabling is required.

Mobile amplifiers with audio shoe technology

The audio shoe is a special connection technology originally developed for hearing aids. Mobile telephone amplifiers with an audio shoe can be used flexibly with various telephones. They are attached to the telephone handset magnetically or using a clamping mechanism and amplify the signal inductively.

This solution is particularly suitable for people who frequently use different telephones, for example at work and at home. The amplifiers are small and lightweight, so they can easily be carried in a pocket. The amplification gain is usually between 15 and 25 dB, which is sufficient for many applications. Modern devices also feature a built-in rechargeable battery that can be charged via USB.

Hearing-impaired telephones with integrated amplification

Hearing-impaired telephones are complete solutions in which the amplification technology is already integrated into the telephone. These special telephones not only offer increased receiver volume of up to 50 dB, but also amplified ring tones of up to 95 dB. Many models feature large, illuminated buttons and an easy-to-read display, making them particularly suitable for older people.

Additional features such as visual call signalling via a flashing light, programmable speed dial buttons and adjustable frequency ranges enhance user comfort. High-quality hearing-impaired telephones from manufacturers such as Humantechnik or Geemarc also offer a hands-free function and are available in both corded and DECT versions.

Modern digital solutions and smartphone apps

Digitalisation has not stopped at hearing aids. Modern smartphones can be converted into effective hearing amplifiers using special apps. These apps use the built-in microphone and amplify ambient sounds or phone calls via headphones or Bluetooth connections to hearing aids.

Some apps even offer individual frequency adjustment based on an integrated hearing test. The amplification settings can be saved for different situations and recalled as needed. For iPhone users, there is also the option to pair compatible hearing aids directly with the phone and amplify calls without additional devices.

Technical specifications and performance features

Understanding amplification power and dB values

Amplification power is measured in decibels (dB) and is the most important performance feature of a telephone amplifier. An increase of 10 dB corresponds to a doubling of the perceived volume. Standard telephones have an output volume of around 65 to 70 dB. With a 30 dB amplifier, you can therefore achieve levels of 95 to 100 dB, which is roughly equivalent to the volume of a passing lorry.

For mild hearing problems, an amplification of 15 to 20 dB is usually sufficient. For moderate hearing loss, 25 to 35 dB is appropriate, whilst severe hearing loss may require amplification of 40 dB or more. It is important to note that excessively high volumes can cause further damage to hearing, which is why many devices feature an adjustable volume limiter.

Tone control and frequency adjustment

In addition to simple volume amplification, tone control plays a key role in speech intelligibility. Many people with hearing difficulties struggle with high frequencies, where important speech sounds such as S, F or T are found. A good telephone amplifier therefore allows for the separate boosting of high frequencies.

Adjustments are usually made via rotary controls or slide switches on the device. Some digital models even offer preset profiles for different types of hearing loss. Frequency adjustment can significantly improve speech intelligibility without the need to increase the overall volume significantly, which is more comfortable for the ears.

Power supply via batteries or mains adapter

The type of power supply has a significant impact on the flexibility and running costs of a telephone amplifier. Battery-powered devices are independent of mains sockets and are well suited for mobile use. Standard AA or AAA batteries last for several months, depending on usage. The disadvantage lies in the ongoing cost of batteries and the risk of them running out at the worst possible moment.

Mains-powered amplifiers offer consistent performance without the need to change batteries. They are ideal for fixed installation on frequently used telephones. Modern devices often feature both options or use rechargeable batteries that can be charged via USB. With average use, battery life usually lasts from several days to weeks.

Compatibility and connection options

Landline telephones and their specific features

Compatibility with various telephone systems is a crucial factor when choosing a telephone amplifier. Wired landline telephones with a modular handset connection (RJ-9 or RJ-22 plug) are the easiest to retrofit. In this case, an inline amplifier can be connected without any modifications.

Retrofitting is more difficult with cordless DECT telephones, as the handset is permanently connected to the base unit. In this case, only mobile amplifiers or a complete replacement with a hearing-impaired telephone are options. Some manufacturers offer special DECT telephones with built-in amplification that can be seamlessly integrated into existing telephone systems.

Hearing aid compatibility via telephone coil

Many modern hearing aids have a built-in telephone coil (T-coil) that can receive electromagnetic signals. Telephone amplifiers with inductive transmission send the amplified signal directly to this coil, thereby minimising background noise. Switching to T-mode usually occurs automatically when the user approaches the telephone handset.

For optimal compatibility, the telephone amplifier should have an adjustable induction strength. The range of inductive transmission is only a few centimetres, which is why the receiver must be held close to the hearing aid. Alternatively, a telecoil loop can be worn around the neck, which transmits the signal over a wider area.

Audio shoe and external connections

The audio shoe is a standardised interface originally developed for professional audio equipment. With hearing aids, it enables the direct connection of external audio sources without any loss of quality. Telephone amplifiers with an audio shoe output can thus be connected to compatible hearing aids without any loss of quality.

The connection is made via a special cable, which is connected to the telephone amplifier at one end and to the audio shoe of the hearing aid at the other. This solution offers the best sound quality, as the signal is transmitted directly without any detours. Modern systems are also increasingly using Bluetooth for wireless transmission, which allows for greater freedom of movement when making calls.

Special features for optimal hearing

Ringer amplifiers and acoustic signals

In addition to call amplification, hearing incoming calls is also problematic for people with hearing loss. Ringtone amplifiers increase the ringtone volume to up to 95 dB, making every call audible. Many devices also offer a choice of different ringtones, as some frequencies are perceived better than others.

The ringtone volume can be adjusted continuously or in predefined steps. Some models feature adaptive volume control that adjusts to the ambient noise level. In noisy environments, the ringtone automatically becomes louder, whilst it is muted at night. This intelligent control prevents missed calls whilst showing consideration for housemates.

Visual and vibrating call alerts

In addition to audible alerts, many hearing-impaired telephones offer visual indicators. Flashing LEDs or signal lights indicate incoming calls even when the ringtone cannot be heard. The light signals are often bright enough to be noticed even out of the corner of the eye.

Vibration signals offer another way of signalling calls. Some telephones have built-in vibration motors, whilst others can be connected to external vibration pads that are placed under the pillow. This combination of audible, visual and tactile signals ensures that no important call is missed.

Telecoil for inductive transmission

The telecoil is a special induction loop worn around the neck that transmits the telephone signal wirelessly to hearing aids with a T-coil. It consists of a thin cable with an integrated coil and a small amplifier, which is usually attached to the belt. The transmission range covers the entire head area.

The advantage of the telecoil lies in its hands-free use. The telephone does not need to be held directly to the ear, which is particularly comfortable during longer conversations. The sound quality is excellent, as background noise is effectively filtered out. Modern telecoils operate on rechargeable batteries and offer a running time of 8 to 12 hours.

Installation and practical use

Step-by-step setup for landline telephones

Installing an inline amplifier is incredibly simple and takes just a few minutes. First, disconnect the handset from the base unit by pulling the modular plug out of the socket. The amplifier is now connected between the telephone and the handset: the handset’s plug goes into the amplifier’s input socket, and the supplied connection cable connects the amplifier to the telephone.

Once the batteries have been inserted or the mains adapter connected, the amplifier is ready for use. The default settings for volume and tone control should initially be left in the middle position. During a test call, the settings can then be adjusted individually until optimal speech intelligibility is achieved.

Connection to hearing aids via various interfaces

Pairing telephone amplifiers with hearing aids requires different procedures depending on the system. For inductive transmission via the T-coil, the hearing aid must be switched to telephone mode. This is done either manually via a switch on the hearing aid or automatically by magnetic sensors when the hearing aid is brought close to the telephone receiver.

For connection via an audio jack, the appropriate adapter is first attached to the hearing aid. The connection cable is then plugged between the telephone amplifier and the audio jack. With Bluetooth-enabled systems, pairing is carried out via the pairing menu. Once set up, the devices connect automatically as soon as they are within range.

Optimal settings for different listening situations

The correct configuration of the telephone amplifier depends on the type of hearing loss and the surrounding environment. For high-frequency hearing loss, the treble boost should be activated, whilst for low-frequency hearing loss, the bass boost helps. The overall volume is set so that speech is clearly intelligible without being uncomfortably loud.

In quiet environments, a moderate gain of 15 to 20 dB is usually sufficient. In the presence of background noise or poor connection quality, the gain can be increased to 25 to 30 dB. It is important to check and adjust the settings regularly, as hearing ability can change over time.

Pricing and where to buy

The price range for telephone amplifiers is wide. Simple inline amplifiers are available from as little as 30 euros, but usually offer only basic functions. Mid-range devices with tone control and higher amplification power cost between 50 and 100 euros. High-quality hearing aid telephones with extensive features cost between 150 and 300 euros.

Specialist hearing aid retailers offer the advantage of expert advice and the opportunity to test devices before purchase. Online shops often have lower prices and a wider selection, but lack personal advice. Some health insurance providers subsidise telephone amplifiers as medical aids if a doctor’s prescription is provided. It is worth checking with your own health insurance provider before making a purchase.

Practical selection criteria

Important features for individual needs

When choosing a telephone amplifier, individual needs should be the main consideration. People with mild hearing problems often find a simple inline amplifier sufficient. For more severe impairments, or if additional features such as visual signalling are required, a hearing-impaired telephone is recommended.

Compatibility with existing devices is another important criterion. Anyone who already wears a hearing aid should ensure it is compatible with T-coils. For people with limited fine motor skills, large buttons and simple operation are important. The ability to save profiles for different users is advantageous in multi-person households.

Seek advice from specialists

Although telephone amplifiers are available over the counter, expert advice is recommended. Hearing care professionals can test your individual hearing ability and recommend suitable devices. They are familiar with the pros and cons of various systems and can help with optimal settings.

Many specialist shops offer the opportunity to test devices for a few days. This is particularly valuable, as the suitability of an amplifier often only becomes apparent in everyday use. Future developments should also be taken into account during the consultation. A high-quality device with reserve amplification capacity can continue to serve you well even as hearing loss progresses.

Further information: Chin-strap headphones or TV hearing amplifiers, Clearvoice technology.