Small horn mouths fail to provide advertised directivity at speech frequencies

Evidence

However, beware of specmanship. One of the authors has seen a loud­ speaker advertised as having a constant directivity of 90°  60° using a horn whose mouth dimensions were 130  130 mm. This gives an Fθmin of 2.4 kHz and 3.4 kHz respectively. As most human speech energy is between 100 Hz and 5 kHz this speaker’s directivity is going to have very little influ­ ence on the intelligibility of the speech! — David Howard, Jamie Angus, coustics and Psychoacoustics, 2497

Categorization

• CANDY: A neat, low-effort anecdote about marketing specmanship in audio gear that any audiophile would enjoy.
• SHARE: Would be great to send to an audio-engineering friend: a concrete example of why horn mouth dimensions matter and how to catch inflated spec claims.
• QUESTION: How commonly does this specmanship appear across consumer and pro audio marketing, and are there standard consumer tools for verifying directivity claims?

Related

• Speaker directivity specifications can be misleadingly marketed without effect on speech intelligibility. (similarity 0.90)
• Horn size physically constrains the frequency range of directional coverage (similarity 0.82)
• Advertised speaker directivity specs can be meaningless for the speech band. (similarity 0.79)
• Constant-directivity horns are efficient but cannot cover frequencies below 500 Hz (similarity 0.79)