Editing Glass harmonica (section)

==Perception of the sound==
The disorienting quality of the ethereal sound is due in part to the way that humans perceive and locate ranges of sounds. Above 4 [[kHz]] people primarily use the ''loudness'' of the sound to differentiate between left and right ears and thus [[Sound localization|triangulate]], or locate the source. Below 1&nbsp;kHz, they use the ''[[phase difference]]s'' of sound waves arriving at their left and right ears to identify location. The predominant pitch of the armonica is in the range of 1–4&nbsp;kHz, which coincides with the sound range where the brain is "not quite sure", and thus listeners have difficulty locating it in space (where it comes from), and discerning the source of the sound (the materials and techniques used to produce it).<ref>{{cite web|url=http://www.bbc.co.uk/radio4/musicfeature/pip/k8ko2/|title= Angelic Organ of Evil|website=BBC|access-date=6 April 2018 | date= October 2007}}</ref>

Benjamin Franklin himself described the harmonica's tones as "incomparably sweet". The full quotation, written in a letter to [[Giambattista Beccaria]], is: "The advantages of this instrument are that its tones are incomparably sweet beyond those of any other; that they may be swelled and softened at pleasure by stronger or weaker pressures of the finger, and continued to any length; and that the instrument, once well tuned, never again wants tuning."<ref name="autogenerated2000"/>

A music critic for ''[[The Morning Chronicle]]'', writing of a performance by Kirchgessner in 1794, said, "Her taste is chastened and the dulcet notes of the instrument would be delightful indeed, were they more powerful and articulate; but that we believe the most perfect execution cannot make them. In a smaller room and an audience less numerous, the effect must be enchanting. Though the accompaniments were kept very much under, they were still occasionally too loud."<ref>{{cite web |work=Haydn Seek |date=October 2016 |title=1794 – The Year part 2 – Time flew – Could it be just 3 weeks? |url=https://www.fjhaydn.com/my-blog/2016/10/1794-the-year-part-2-.html}}</ref>{{better source needed|date=July 2023}}