Combinations of consonants with [r]. Double assimilation of clusters [tr, dr, Өr, str]

Double assimilation
Train – in the cluster of the voiceless consonant [t] with the sonorant [r] complete devoicing of the sonorant [r] takes place (progressive assimilation affecting the work of the vocal cords) and under the influence of the post-alveolar sonorant [r] consonant [t] becomes post-alveolar (assimilation affecting the place and the manner of articulation). Thus, double assimilation takes place.

Double assimilation
Street - in the cluster of the voiceless consonants [st] with the sonorant [r] partial devoicing of the sonorant [r] takes place (progressive assimilation affecting the work of the vocal cords) and under the influence of the post-alveolar sonorant [r] consonant [t] becomes post-alveolar (assimilation affecting the place and the manner of articulation). Thus, double assimilation takes place.

Double assimilation
Dry - in the cluster of the voiced consonant [d] with the sonorant [r] the last ([r]) becomes fricative and under the influence of the post-alveolar sonorant [r] consonant [d] becomes post-alveolar (assimilation affecting the place and the manner of articulation). Thus, double assimilation takes place.

Double assimilation
Bathroom - in the cluster of the voiceless interdental consonant [Ө] with the sonorant [r] partial devoicing of the sonorant [r] takes place (progressive assimilation affecting the work of the vocal cords) and under the influence [Ө] the post-alveolar sonorant [r] is replaced by an alveolar tap: a single brief tap is made by the tip of the tongue on the teethridge. Thus, double assimilation takes place.

Combinations of voiceless consonants with [r]
Progressive assimilation in clusters [pr, kr, skr, fr, ∫r]

Friend - in the cluster of the voiceless consonant [f] with the sonorant [r] partial devoicing of the sonorant [r] takes place. Thus, progressive assimilation affecting the work of the vocal cords.
This kind of assimilation is observed in the clusters [skr, ∫r]: scream, shrewd.

Proud - in the cluster of the voiceless consonant [p] with the sonorant [r] complete devoicing of the sonorant [r] takes place. Thus, progressive assimilation affecting the work of the vocal cords. This kind of assimilation is observed in the cluster [kr]: cry.

Warning!!!
Partial devoicing of the sonorant [r] is observed in the clusters [kr, tr, pr] if they are in an unstressed position, at a word boundary or [p,t,k] are preceded by some fricative consonants ([s]): temperature, waitress, quite right.

Combination of voiced consonant [ð] with [r]
Progressive assimilation in the cluster [ðr]