J. C. Wells, the phonetician, in his Pronunciation Dictionary (Longman, 3rd edition 2008) gives three possibilities for British English.
ˈpɑ:t ɪs ɪp l, the most common pronunciation (spaces make the syllabification of the word clear)
ˈpɑ:ts ɪp l, less common with only three syllables
pɑ: ˈtɪs ɪp l, also less common than the first one with the stress on the ...
Is "participle" pronounced with stress on the first syllable or the second syllable?
(Received Pronunciation) IPA: /pɑːˈtɪsɪpəl/
(US) IPA: /ˈpɑɹtɪˌsɪpəl/
So some people stress the first syllable and some people stress the second syllable. According to Wiktionary, people in the US are more ...
It is a participle. You can tell this because it qualifies (describes) "they", the subject of the verb. Being a participle, it is a kind of adjective: a verbal adjective. that is, it is an adjective formed from a verb base - in this case, hear.
Now in the following sentence, hearing is a so-called gerund.
Hearing the sound was the most significant ...
The cat was surrounded by mice - is the PV of 'Mice surrounded the cat.' If we go by PV, it can be analyzed as, a) The cat (sub) and was surrounded (passive verb). If seen as in a) The cat was injured.... The was attacked.... The cat was surrounded...., the part after 'The cat was' can be considered verb complement or even adjectival (The cat was fat/ ...