Run inference with a pipeline and specify which vocoder to use
thon
from transformers import pipeline, FastSpeech2ConformerHifiGan
import soundfile as sf

vocoder = FastSpeech2ConformerHifiGan.from_pretrained("espnet/fastspeech2_conformer_hifigan")
synthesiser = pipeline(model="espnet/fastspeech2_conformer", vocoder=vocoder)
speech = synthesiser("Hello, my dog is cooler than you!")
sf.write("speech.wav", speech["audio"].squeeze(), samplerate=speech["sampling_rate"])