There is some overlap between the readings in these two books. Ladefoged & Johnson is available as an ebook. However, there is material in Ladefoged’s ‘Elements of acoustic phonetics’ that is not covered in Ladefoged & Johnson.
Reading
Handbook of phonetic sciences – Ch 20 – Intro to Signal Processing for Speech
Written for a non-technical audience, this gently introduces some key concepts in speech signal processing.
Ladefoged (Elements) – Chapter 4 – Wave analysis
The waveform is rarely the best representation for analysis of sound, and this is an intuitive introduction to why.
Ladefoged (Elements) – Chapter 5 – Resonance
Now we turn to speech production, and resonance is how the vocal tract shapes the quality of sound, to produce different vowels, for example.
Ladefoged (Elements) – Chapter 8 – Resonances of the vocal tract
A more detailed look at how resonance occurs in the vocal tract, and how that can be used to explain the sound quality (e.g. formant frequencies) of vowel sounds.
Ladefoged & Johnson – A course in phonetics – Chapter 8 – Acoustic phonetics
Links the source-filter model to spectrograms and acoustic analysis of speech.