What is Pure-Tone Testing?

pure tone testing

Have you ever wondered how audiologists assess the degree and kind of hearing loss? One of the tools they use is pure-tone testing. This standard and simple test is critical for evaluating hearing by measuring the quietest sounds you can hear at different pitches.

Understanding what pure-tone testing is can make the hearing assessment process less intimidating and show how important it is for diagnosing and managing hearing issues.

The Science Behind Pure-Tone Testing

To understand what a pure-tone hearing test is and how it works, knowing the basics of how humans hear work is helpful. Hearing relies on complex structures in the ear that convert sound waves into signals the brain can understand.

Sound waves enter the outer ear and travel through the ear canal. These waves then cause vibrations of the eardrum and the tiny bones behind it called ossicles. The ossicles transmit and amplify these vibrations into the inner ear, creating fluid waves inside the cochlea – the snail-shaped hearing organ.

The cochlea converts these mechanical waves into electrical signals using thousands of specialized receptor hair cells arranged across different regions of the cochlea. Each set of hair cells responds to a specific frequency. Higher frequency hair cells are located near the base, while lower frequency receptors lie at the apex.

This arrangement, known as tonotopic organization, allows different pitches to create a spatial pattern of activity across the hair cells. The auditory nerves then carry these complex signals to the brain to interpret as meaningful sounds.

Pure-tone testing identifies the lowest thresholds at which this complex system can perceive sounds across the audible frequency spectrum, typically ranging from 125 Hz to 8000 Hz. Charting these thresholds on an audiogram provides a comprehensive view of your hearing sensitivity.

Pure-Tone Testing Process

Pure-tone testing is usually performed by an audiologist, ENT specialist, or hearing healthcare professional. Ensuring accurate results requires appropriate preparation and a controlled testing environment. The test typically follows these steps:

  • Preparation. The ENT checks the exterior of your ear for blockages. They’ll also remove earwax or debris if present. They may also perform a basic otoscopic examination to visualize the eardrum and ensure there are no issues. You’ll also receive basic instructions on the pure-tone testing process and how to signal when tones are heard.
  • Transducer and ear selection. The audiologist determines appropriate transducers like circumaural headphones, insert earphones, or bone conductors. They’ll choose the transducer based on specific factors like ambient noise levels, the presence of collapsing ear canals, and your comfort. Because your ears are tested individually, your audiologist will randomly select an initial testing ear.
  • Set test frequencies and levels. The full range of test frequencies is usually 250 Hz to 8000 Hz. The initial stimulus level is set above estimated thresholds, usually at 70-80 dB HL. A higher level near 100 dB HL may be used for children or those with profound loss.
  • Presentation of tones. The test involves 1-2 seconds long tone presentations, separated by silent intervals. Tones are pulsed or warbled to avoid standing waves. Each frequency is tested individually in a fixed low to high pitch order— you’ll signal (by a button press or raised hand) when you hear the test tone.
  • Threshold determination. When you detect the signal, the healthcare providers will reduce the tone intensity in 10 dB steps until you no longer report the tone for at least 50% of trials. The lowest level of positive responses, at least 50% of the time is noted as the frequency threshold.
  • Test other ear. The same procedure is repeated to obtain thresholds for the other ear unless the hearing loss is suspected in just one ear. Your healthcare provider may mask the untested ear once they’ve obtained the first ear’s results.
  • Bone conduction testing. This testing can assess if the hearing loss is from outer/middle ear issues versus inner ear problems. A bone oscillator will be placed on the mastoid to deliver tones directly to the cochlea, bypassing the external and middle ear.
  • Plot audiogram. The specific frequency thresholds measured by your healthcare provider will be marked on an audiogram chart to give a clear overview of your hearing ability.

Interpreting Pure-Tone Testing Results

Your level of hearing loss can be determined by checking where the hearing threshold line is on an audiogram. This line helps classify how severe the hearing loss is. Some common hearing loss thresholds include:

Hearing Level in Decibels (dB) Hearing Status
-10dB to 15dB Normal hearing
16dB to 25dB Possible slight loss
26dB to 40dB Mild hearing loss
41dB to 55dB Moderate hearing loss
56dB to 70dB Moderately severe loss
71dB to 90dB Severe hearing loss
Above 90dB Profound hearing loss

Type of Hearing Loss

Pure-tone tests can assess various types of hearing loss, helping your healthcare provider prescribe targeted treatments like hearing aids or surgery to help remedy the issue. The main types of hearing loss include:

  • Conductive loss. Conductive hearing loss occurs when issues in the external or middle ear block sound transmission. It’s identified by an air-bone gap greater than 10 decibels in audiometric tests.
  • Sensorineural loss. Sensorineural hearing loss occurs due to inner ear or auditory nerve damage. It’s characterized by similar levels of hearing loss in both air and bone conduction tests, indicating a deterioration in the ability to perceive sound regardless of the transmission method.
  • Mixed hearing loss. Mixed hearing loss is a combination of conductive and sensorineural types. It shows air-bone gaps indicative of middle ear issues and cochlear damage affecting inner ear function.

The results of a pure-tone test can reveal the underlying causes of hearing loss. For instance, the test may indicate a uniform loss across all pitches, known as ‘flat’ loss, or a decline that worsens at high or low pitches, referred to as ‘high-frequency sloping’ or ‘low-frequency sloping’ loss. Occasionally, there may be a pronounced decrease in hearing at specific frequencies, a condition termed ‘notching.’

By looking closely at the results of a pure-tone test, including how severe the hearing loss is, what type it is, and its pattern (or configuration), your healthcare provider can gain valuable information to help understand your hearing issues.

Need a hearing aid

Different Types of Pure-Tone Tests

There are two main types of pure-tone hearing tests based on how signals are transmitted to the inner ear:

Air Conduction Test

This technique uses headphones or inserts for tone delivery into the external auditory canal to assess the conductive pathway. The sound waves stimulate the ossicles before the inner ear conversion into neural signals. It tests functionality across outer, middle, and inner ear structures. Air conduction typically provides information on the degree of hearing loss.

Bone Conduction Test

In this method, a bone oscillator transducer is positioned on the mastoid bone behind the ear to transmit vibrations. This directly stimulates the inner ear through bone conduction, allowing for the detection of the auditory nerves’ responses without involving the external and middle ear.

Analyzing the differences between air conduction and bone conduction results is crucial for differentiating between conductive issues in the outer/middle ear and sensorineural damage in the cochlea or auditory nerve, identifying the location of hearing impairment.

Limitations and Challenges of Pure-Tone Testing

While indispensable for hearing evaluations, pure-tone audiometry does have some limitations and testing challenges to consider:

  • Difficulty testing infants and young children. Obtaining reliable pure-tone thresholds requires a certain degree of patient understanding and cooperation, making it challenging to perform accurate assessments in children younger than five. Techniques like visual reinforcement or conditioned play audiometry might provide estimates, though they lack precision.
  • Inability to identify specific hearing disorders. Pure-tone testing offers detailed quantitative insights into hearing loss – its degree, type, and configuration. However, it falls short of identifying the specific pathological origin or cause. A comprehensive evaluation, including patient history, physical examination, and advanced audiological assessments, is essential to diagnose particular disorders accurately.
  • Possibility of intentional exaggeration. Since pure-tone audiometry depends on patient responses, there is a chance that individuals provide false responses, leading to pseudohypacusis – falsely exaggerated hearing loss.
  • Ambient noise interference. External sounds in the testing environment can interfere with signals, possibly affecting results. Proper soundproofing of audiometric testing booths may help address this issue.

The Role of Pure-Tone Testing in Overall Hearing Assessment

Pure-tone audiometry forms the foundation for comprehensive hearing evaluations by providing critical quantitative data on the degree, type, and configuration of hearing loss. However, due to its limitations, results must be combined with other subjective and objective audiological tests for an accurate and holistic assessment.

Speech audiometry techniques like speech reception threshold (SRT) testing or word recognition scores help assess how speech perception corresponds with pure-tone thresholds. Otoacoustic emissions (OAEs), auditory brainstem response (ABR), and other electrophysiological tests can confirm pure-tone audiometry findings.

Here are several important ways in which pure-tone thresholds enhance other testing approaches:

  • Compare SRT and word recognition scores against pure-tone average (PTA) – significant mismatches can indicate issues
  • OAE and ABR tests provide objective cochlear/neural measurements to cross-verify and confirm sensorineural loss
  • Specialized speech-in-noise or central auditory processing testing reveals modulation deficits not obvious in pure-tone audiometry

My Pure-Tone Test Shows Moderate Hearing Loss, Now What?

Being diagnosed with moderate hearing loss might seem overwhelming, but modern hearing technologies offer excellent solutions. Schedule a consultation with your healthcare provider to:

  • Discuss the severity, type, and pattern of your hearing loss to fully understand your specific hearing challenges.
  • Explore suitable hearing aid types and technology levels for your situation.
  • Look into hearing assistive devices like remote microphones, TV streamers, and visual fire alarms to enhance hearing aid effectiveness.
  • Adopt communication strategies such as facing the speaker, reducing background noise, and ensuring attention before speaking to save mental energy.
  • Consider trial periods for testing various hearing aids to find the best fit for comfort and sound clarity before committing to a purchase.

At Analog Hearing Labs, our TrueEQ hearing aids combine the highest-grade hybrid analog amplification technology with premium medical-grade components sourced from industry leaders such as Sonion and Knowles. This commitment to excellence ensures that our hearing aids stand out in the market for their durability, performance, and user satisfaction.

The benefits of choosing TrueEQ hearing aids extend beyond the superior sound quality. Our hearing aids offer a listening experience as close to natural hearing as possible, thanks to their precise amplification and the ability to fine-tune frequencies to match individual hearing profiles.

Users enjoy a more comfortable listening experience with less fatigue, making staying connected in conversations and engaged in daily activities easier. Our dedicated team provides personalized support to ensure that each user finds the perfect fit and gets the most out of their TrueEQ hearing aids, enhancing their overall quality of life.

Hearing aid in ear

Support Your Auditory Health With Analog Hearing Labs

Hearing loss can affect almost every aspect of your life, from professional success and social connections to safety and quality of life. Fortunately, innovative hearing technology can support auditory rehabilitation and restore function for mild to moderate loss.

Our licensed specialists are ready to review your audiogram to determine if TrueEQ hearing aids can enhance your auditory health. Contact us today to try TrueEQ for 45 days risk-free and experience crystal-clear hearing.

Recent Posts

Hearing impairment using hearing aid
  • Apr 30, 2024
  • Post by analoghearingaids
Depending on your age, health condition, and other circumstances, the sounds you…
Hearing Solution
  • Apr 25, 2024
  • Post by analoghearingaids
According to a 2021 National Center for Health Statistics (NCHS) report, hearing…
Anatomy of the human ear
  • Mar 22, 2024
  • Post by analoghearingaids
Curious about how noise vibration turns into sound? While most of us…
Call Now Button