Professional Tone Generator

Synthesize pure audio frequencies to evaluate acoustics, hardware, and hearing thresholds. Generate signals from $20\text{Hz}$ to $20,000\text{Hz}$ with studio-grade logarithmic precision.

440

HERTZ (Hz)

20 Hz 440 Hz 20k Hz

Waveform Type

Output Level

Professional Tone Generator (20 Hz – 20 kHz Sine & Waveforms)

Generate precise audio frequencies from 20 Hz to 20,000 Hz directly in your browser. This professional tone generator lets you produce sine, triangle, square, and sawtooth waveforms for speaker testing, headphone evaluation, room acoustics checks, pitch reference, and educational demonstrations.

All tones are digitally synthesized using standard oscillator methods. No microphone access is required. Output level is adjustable, and frequencies can be selected manually or by range presets.

Always begin at a low volume and increase gradually. High frequencies and strong amplitudes can be uncomfortable or harmful at excessive levels.

What Is a Tone Generator?

A tone generator produces a continuous audio signal at a selected frequency, measured in Hertz (Hz). In acoustics and audio engineering, test tones are used to:

Evaluate speaker frequency response
Detect distortion or rattling
Check headphone channel balance
Identify room resonance issues
Reference musical pitch (e.g., 440 Hz)

If you need a refresher on how frequency relates to perceived sound, review our overview of sound pressure level (SPL) and how acoustic waves are measured.

Understanding the Audible Frequency Range (20 Hz – 20 kHz)

Human hearing typically spans from approximately 20 Hz to 20 kHz, although the upper limit declines with age.

Sub-Bass (20–60 Hz)

Felt more than heard
Tests subwoofer extension
Common source of room resonance

Laptop and phone speakers rarely reproduce this range accurately.

Bass & Low Mids (60–500 Hz)

Fullness and warmth
Common area for boominess
Useful for testing enclosure vibrations

Midrange (500 Hz – 4 kHz)

Critical for speech intelligibility
Most sensitive region of hearing
Ideal for testing clarity

Highs & Air (10 kHz – 20 kHz)

Brilliance and detail
Often difficult for older listeners to hear above 16–18 kHz

For a broader explanation of decibel perception and scaling, see our guide to the logarithmic decibel scale.

Waveform Types Explained

Different waveforms contain different harmonic structures. This affects how the tone sounds and how equipment responds.

Sine Wave (Pure Tone)

Single frequency only
No harmonics
Ideal for calibration and hearing checks

Triangle Wave

Contains odd harmonics
Softer than square wave
Useful for harmonic testing

Square Wave

Strong odd harmonics
Sharper, more aggressive sound
Useful for identifying distortion

Sawtooth Wave

Contains all harmonics
Bright and buzzy
Useful for testing full-spectrum response

Harmonic Comparison

Waveform	Harmonics Present	Typical Use
Sine	None	Calibration, hearing
Triangle	Odd (reduced amplitude)	Harmonic evaluation
Square	Odd (strong)	Distortion detection
Sawtooth	All	Full-range response testing

If you want to analyze the harmonic content visually, use our frequency analyzer alongside this generator.

How This Online Tone Generator Works

Digital Oscillator

The tool uses a browser-based oscillator to synthesize a waveform mathematically at the selected frequency. The waveform is generated in real time using standard digital signal processing techniques.

Frequency Precision

Frequency values are expressed in Hertz (cycles per second). Precision is limited by the browser’s audio sample rate (commonly 44.1 kHz or 48 kHz).

Nyquist Consideration

The Nyquist frequency is half the sample rate. For a 44.1 kHz system, frequencies above ~22 kHz cannot be reproduced accurately. Since this generator caps at 20 kHz, it remains within typical playback constraints.

Output Level Control

The output slider adjusts amplitude through a gain control stage. It does not calibrate to a specific SPL. Perceived loudness depends entirely on your playback device.

If you need to convert SPL values to physical pressure units for calibration reference, use our SPL converter.

How to Generate a Test Tone (Step-by-Step)

Select a frequency using the slider or preset bands.
Choose a waveform type.
Lower your system volume.
Press Start Signal.
Gradually increase output level if needed.

Stop playback immediately if you experience discomfort or ringing.

Interpreting What You Hear

Use the table below as a diagnostic guide.

Frequency Range	Expected Perception	Possible Issue If Distorted
20–60 Hz	Rumble / vibration	Weak subwoofer extension
100–300 Hz	Warm bass	Cabinet resonance
1–4 kHz	Clear tone	Harshness or clipping
10–15 kHz	Sharp, bright	Tweeter distortion

If you detect uneven response, you may compare before/after adjustments using our volume level comparator.

Testing Speakers and Headphones

Speaker Sweep Method

Start at 50 Hz.
Increase gradually in 50–100 Hz increments.
Listen for rattles, distortion, or sudden level changes.

Room interactions can create standing waves. To assess environmental noise interference before testing, run our background noise test.

Subwoofer Check

Subwoofers should reproduce 20–80 Hz smoothly. Significant drop-offs below 40 Hz are common in compact systems.

Headphone Testing

Headphones should maintain consistent loudness across frequencies. Sharp peaks or dips may indicate driver imbalance.

Hearing Self-Check (Non-Diagnostic)

This tone generator can help you explore your hearing range, but it is not a medical test.

Suggested process:

Start at 1,000 Hz at low volume.
Gradually increase toward higher frequencies.
Stop immediately if discomfort occurs.

Most adults over 30 cannot hear much above 16–18 kHz. Extended exposure to loud tones may contribute to hearing damage. For safety benchmarks, review our hearing damage dB chart.

If you are evaluating exposure levels, consult the noise exposure calculator.

Accuracy & Limitations

This tool synthesizes mathematically accurate waveforms, but output quality depends on:

Device speakers or headphones
Audio interface quality
System volume calibration
Room acoustics

Limitations include:

Laptop speakers often roll off below 100 Hz.
Phone speakers cannot reproduce deep bass accurately.
Hearing sensitivity varies by individual and age.
This is not a certified calibration instrument.

For a detailed discussion of measurement reliability, see our guide to online decibel meter accuracy.

Common Mistakes

Starting at high volume.
Expecting phone speakers to reproduce 20 Hz accurately.
Confusing harmonic distortion with frequency imbalance.
Using square waves for hearing checks instead of sine waves.
Testing in noisy environments.

To better understand acoustic energy levels during playback, review what a decibel is.

Frequently Asked Questions

How do I generate a 440 Hz tone?

Move the frequency slider to 440 Hz or enter the value if manual input is available. 440 Hz corresponds to the musical note A4, the standard concert pitch reference.

Is 20 kHz audible?

In theory, 20 kHz is within the upper limit of human hearing. In practice, many adults cannot hear above 16–18 kHz due to natural age-related changes.

What is a sine wave?

A sine wave is a pure tone containing a single frequency with no harmonics. It is the standard waveform used for calibration and hearing checks.

Why does a square wave sound harsher?

Square waves contain strong odd harmonics, which add high-frequency content. This makes them sound brighter and more aggressive than sine waves.

Can this tool test my hearing?

It can help you explore your hearing range informally, but it is not a medical diagnostic tool. Professional audiometry is required for clinical assessment.

How do I test subwoofer frequencies?

Start at 30–40 Hz and gradually move upward. Listen for consistent output without rattling or distortion. Many small speakers cannot reproduce deep sub-bass.

What frequency is best for calibration?

Common calibration tones include 1,000 Hz and 94 dB reference tones. Calibration accuracy depends on external measurement equipment.

Does this work on phone speakers?

Yes, but phone speakers have limited low-frequency response. Deep bass reproduction below ~100 Hz may be inaccurate.

What is harmonic distortion?

Harmonic distortion occurs when additional frequencies are introduced beyond the fundamental tone. Square and sawtooth waves intentionally contain harmonics.

Is this tone generator accurate?

The frequency synthesis is mathematically precise within browser audio constraints. However, perceived output depends on hardware quality and playback calibration.

Free Tone Generator – Audio Frequency Tool