Online tone synthesizer with pure waveforms
Sweep through a range of frequencies to test speakers, identify room resonances, or check your hearing range. Essential for audio testing and calibration.
Disclaimer: This is not a medical hearing test. Results are for informational purposes only and cannot replace professional audiometry. If you have concerns about your hearing, please consult an audiologist or ENT specialist.
Test your ability to hear different frequencies. For best results, use quality headphones in a quiet environment. Start at a comfortable volume.
Click each frequency and indicate if you can hear it clearly.
High-frequency hearing naturally decreases with age (presbycusis):
Set second tone relative to first
Standard reference frequencies for instrument tuning, audio calibration, and testing. Click any frequency to play it instantly.
A4=440 Hz adopted as ISO 16 standard in 1955
Standard guitar tuning EADGBE
Drop D tuning - 6th string down one tone
4-string bass standard tuning
5-string bass with low B
Soprano/Concert/Tenor ukulele
Standard violin tuning in fifths
One fifth below violin
One octave below viola
Middle octave of the piano
Standard test tones for speaker and hearing tests
North American telephone signaling tones
Understanding sound waves, frequency, and psychoacoustics is fundamental to audio engineering, music, and hearing science. This guide covers the essential principles with references to key research.
The purest tone possible, containing only the fundamental frequency with no harmonics. Sine waves are the building blocks of all other sounds - any complex waveform can be decomposed into a series of sine waves through Fourier analysis, as demonstrated by Joseph Fourier in 1822.
Harmonics: Fundamental only
Character: Pure, smooth, clean
Uses: Tuning, calibration, sub-bass
Contains only odd harmonics (1st, 3rd, 5th, 7th...) at amplitudes of 1/n. This creates a hollow, woody sound reminiscent of vintage synthesizers and clarinet-like tones. The absence of even harmonics gives it a distinctive hollow character.
Harmonics: Odd only (1, 3, 5, 7...)
Character: Hollow, woody, buzzy
Uses: Synthesis, 8-bit sounds, testing
Contains all harmonics (odd and even) at amplitudes of 1/n. This gives it the richest harmonic content of the basic waveforms, producing a bright, buzzy, brass-like sound. Excellent as a starting point for subtractive synthesis.
Harmonics: All (1, 2, 3, 4, 5...)
Character: Bright, brassy, rich
Uses: Lead synths, strings, brass
Contains only odd harmonics like square waves, but at amplitudes of 1/n squared, making the higher harmonics much weaker. This results in a softer, rounder sound - somewhere between sine and square.
Harmonics: Odd only (weaker)
Character: Soft, mellow, rounded
Uses: Flutes, soft leads, LFOs
Psychoacoustics is the scientific study of sound perception, bridging physics and psychology. Understanding these principles is essential for audio engineering and music production.
Human hearing is not equally sensitive across all frequencies. Fletcher and Munson's 1933 research, later refined by Robinson and Dadson (1956) and standardized as ISO 226:2003, showed that:
The cochlea divides sound into approximately 24 critical bands (Bark scale). This has important implications:
The relationship between frequency and musical pitch is fundamental to music theory and acoustic science.
The modern Western music system divides the octave into 12 equal semitones:
When a string or air column vibrates, it produces not just the fundamental but a series of harmonics at integer multiples:
Sound enters the ear canal, causing the eardrum to vibrate. These vibrations are transmitted through the ossicles (malleus, incus, stapes) to the cochlea, where hair cells convert mechanical motion into neural signals.
Based on NIOSH and WHO recommendations: