Fig 1.
The spectrogram (from 0 to 5000 Hz) of an example speech (i.e., Sentence 26: /ʈʂɤ4/ /ɕja4/ /uɔ3/ /kʰɤ3/ /i3/ /xwan4/ /ʂoʊ3/ /tɕi1/ /lɤ0/) produced by of the early (bottom), sustained (middle), and long-term (top) abstinent heroin users.
Fig 2.
The mean value (standard deviation as error bars) of the frequency-related acoustic parameters of the early (i.e., < 2 years), sustained (i.e., 2 years), and long-term abstinent heroin users (i.e., > 2 years).
Fig 3.
The mean value (standard deviation as error bars) of the amplitude-related acoustic parameters of the early (i.e., < 2 years), sustained (i.e., 2 years), and long-term abstinent heroin users (i.e., > 2 years).
Fig 4.
The mean value (standard deviation as error bars) of the spectral-related acoustic parameters of the early (i.e., < 2 years), sustained (i.e., 2 years), and long-term abstinent heroin users (i.e., > 2 years).
Fig 5.
The mean value (standard deviation as error bars) of the temporal-related acoustic parameters of the early (i.e., < 2 years), sustained (i.e., 2 years), and long-term abstinent heroin users (i.e., > 2 years).
Table 1.
The mean values (standard deviations) of the nineteen acoustic features of the three groups of abstinent heroin users (i.e., the early, sustained, and long-term abstinent users).
Table 2.
The results of linear-mixed effect models on the nineteen acoustic features.
In each model, the duration of drug detoxification (i.e., the early [< 2 years], sustained [= 2 years], and long-term [> 2 years] abstinent heroin users) was fixed effect.