Section 5 of it deals with "Airstream mechanisms". The majority of sounds produced as allophones of phonemes are pulmonic egressive ones, i.e. the air flows from the lungs to the oral and/or nasal cavity. As this stream of air passes through the larynx it can either be modified to produce voice or "it may flow without interruption through the open glottis and remain voiceless (for sounds such as [p s ʧ]" (p. 69). What about the glottal stop?
And then we are informed of some instances of pulmonic ingressive airstream events, e.g. in a dialect of an Austronesian language. What fascinated me much more, however, was a fact, hitherto completely unknown to me, yet existing in the not so distant neighbourhood - namely that there exists a "Fensterle region" (p. 69) in Switzerland. Wow! I was aware of the habit of 'fensterln', a verb which describes an old-fashioned courting custom (old-fashioned because we now have mobiles, smartphones, internet) of young men who tried to climb into the chambers of their girlfriends through the window (= 'Fenster'). What sense does it make to disguise your voice while you're courting a girl? She won't recognise you later on. This custom was not restricted to the Alpine region but could be found throughout Central and Northern Europe. But I was not aware of the fact that those young men talked while breathing in to disguise their voices. I wouldn't have termed the area 'Fensterle region' because the '-le' as a diminutive suffix rather denotes a tiny window (probably too small for the young man to climb through). Maybe, 'Fensterln region' would have been more appropriate (or 'Kiltgang region' to use a term taken from the Historisches Lexikon der Schweiz (see headword Kiltgang)).
Section 6 is devoted to the description of vowels. Mentioning and explaining the Cardinal Vowel System is a must here, and the author does explain them in detail. In ch. 6.2.5 P. Ashby tries to introduce the phonetic novice to the acoustic fundamentals of voiced sounds by explaining concepts such as periodic and aperiodic waveforms, simple and complex ones, superimposition of sinusoidals, amplitude, spectrogram - all this on roughly six pages. As I wrote in my previous blog entry: "I strongly doubt that a beginner will be able to appreciate all this." Less would have been more.