Diffraction is a fundamental wave phenomenon that explains why you can hear someone speaking around a corner. When sound waves encounter an obstacle or opening, they bend around edges and spread out. The degree of diffraction depends on the relationship between wavelength and obstacle size: waves diffract strongly around objects smaller than their wavelength and cast sharper shadows around objects much larger than their wavelength.

At 100 Hz, sound has a wavelength of about 3.4 meters — it diffracts readily around most architectural features, furniture, and even walls. At 10 kHz, the wavelength is only 34 mm, so even a person's head creates a significant acoustic shadow. This frequency-dependent behavior has profound implications for sound system design, room acoustics, and measurement practices.

In loudspeaker design, diffraction from cabinet edges creates ripples in the frequency response as diffracted waves interfere with the direct radiation. Rounded cabinet edges, waveguides, and flush-mounting mitigate these effects. Outdoor sound barriers exploit the limited diffraction at high frequencies to create quiet zones, while accepting that low-frequency sound will bend over the barrier with minimal attenuation.

For acoustic measurements with SonaVyx, diffraction affects microphone placement decisions. A microphone mounted on a surface (boundary measurement) eliminates reflections from that surface but may introduce diffraction effects from surface edges. The transfer function measurement reveals diffraction-related irregularities in frequency response. The speaker measurement tool shows cabinet diffraction effects that become apparent when comparing on-axis and off-axis responses. Understanding diffraction helps interpret measurement results and optimize microphone positions.