Pure Tone Audiometry – The Cornerstone of Hearing Diagnosis

Introduction

Pure Tone Audiometry (PTA) is the most widely used test in audiology. It measures hearing thresholds across different frequencies and intensities, helping clinicians understand the degree and type of hearing loss. While PTA is common, it is crucial to distinguish between screening audiometry and diagnostic audiological testing.

• Screening Hearing Testing – Important but Limited

  • Purpose: To quickly identify individuals who may have hearing loss.

  • Method: Limited-frequency testing, often conducted in schools, workplaces, or community health programs.

  • Outcome: Pass/Fail result.

  • Who Can Perform: ENT doctors, nurses, and trained technicians can conduct screening audiometry.

  • Importance: Screening is vital for early detection, especially in children and at-risk populations, ensuring timely referral for further evaluation.

  • Limitation: It does not provide detailed information about the type or severity of hearing loss.

    
    

• Diagnostic Hearing Testing – Comprehensive Evaluation

  • Purpose: To thoroughly evaluate hearing ability and pinpoint the exact nature of the problem.

  • Method: Comprehensive PTA across a wide range of frequencies and intensities, performed in a sound-treated environment.

  • Outcome: Detailed audiogram showing air conduction and bone conduction thresholds.

  • Who Should Perform: Only a qualified audiologist should conduct diagnostic audiological tests, as they require specialized expertise to interpret results accurately and plan appropriate interventions.

Why Diagnostic Pure Tone Audiometry Matters

Screening can only flag potential issues, but diagnostic PTA provides the complete picture. It is essential for:

• Determining the exact degree of hearing loss.

• Differentiating between conductive, sensorineural, and mixed hearing loss.

• Guiding precise treatment options such as medical management, surgery, or hearing aid fitting.

The Role of Speech Audiometry

Hearing pure tones is one thing, but real-life communication depends on understanding speech.

• Speech Reception Threshold (SRT): Identifies the lowest level at which speech can be understood.

• Word Recognition Score (WRS): Evaluates clarity of speech perception at comfortable listening levels.

  
  

  Together with PTA, speech audiometry ensures that patients not only hear sounds but also comprehend speech effectively.

To fully understand a patient’s hearing problem, audiologists often combine PTA and speech audiometry with other tests:

• Impedance Audiometry (Tympanometry & Acoustic Reflexes): Assesses middle ear function.

• Otoacoustic Emissions (OAE): Evaluates cochlear (outer hair cell) function.

• Brainstem Evoked Response Audiometry (BERA/ABR): Checks neural pathways up to the brainstem.

These tests provide a holistic view of auditory health, ensuring no aspect of the hearing system is overlooked.

In-Situ Audiometry Through Hearing Aids – Why It Is Unreliable

Some modern hearing aids offer in-situ audiometry, where hearing thresholds are measured directly through the device itself. While convenient, this method has significant limitations:

• Calibration Issues: Hearing aids are not calibrated like clinical audiometers, leading to inaccurate threshold measurements.

• Environmental Factors: Testing is often done outside sound-treated rooms, introducing background noise and variability.

• Limited Frequency Range: In-situ testing may not cover the full spectrum of frequencies needed for precise diagnosis.

• Risk of Misinterpretation: Results can mislead patients and clinicians if relied upon without proper diagnostic testing.

Therefore, while in-situ audiometry may assist in fine-tuning hearing aids, it cannot replace diagnostic PTA performed by a qualified audiologist.

Providing Appropriate Treatment Options

A comprehensive diagnostic approach allows audiologists to:

• Recommend medical or surgical interventions when necessary.

• Fit and fine-tune hearing aids based on both PTA and speech audiometry results.

• Plan auditory rehabilitation strategies for patients struggling with speech understanding.

• Offer counseling and communication strategies tailored to each patient’s unique needs.

Conclusion

Pure Tone Audiometry is more than just a test—it is the foundation of hearing care. While screening audiometry is important and can be performed by ENTs, nurses, and technicians, diagnostic audiological tests must only be conducted by qualified audiologists. In-situ audiometry through hearing aids may seem convenient but is unreliable for diagnosis.

When combined with speech audiometry and other RCP tests, diagnostic PTA provides the depth of information needed to design effective treatment plans. Ultimately, the goal is not just to help patients hear but to help them understand and communicate with confidence.