## 2 Related Work  
### Speech Audiometry  
Speech audiometry is a critical hearing assessment used to evaluate an individual's speech recognition ability, directly measuring their capacity to comprehend spoken language in real-life situations [10]. Unlike PTA, this test involves presenting speech sounds and assessing how accurately they can be understood. Speech audiometry evaluates a patient's ability to perceive and distinguish speech sounds at various intensity levels. It plays a crucial role in determining their auditory condition and the necessity for hearing assistive devices such as hearing aids or cochlear implants [11].  
The threshold values used in speech audiometry, namely the speech recognition threshold (SRT) and the speech detection threshold (SDT), are crucial indicators for auditory assessment, enabling the quantitative measurement of a patient's speech recognition and detection abilities. SRT refers to the lowest sound intensity (dB HL) at which a patient can minimally recognize speech, and it is typically measured as the minimum intensity at which speech is correctly recognized 50% of the time (SRT 50) [12]. During the test, monosyllabic or disyllabic words are presented at varying intensity levels, and the lowest level at which the patient correctly recognizes a specified percentage of speech is recorded as the threshold [13]. SRT serves as an essential benchmark for evaluating a patient's overall hearing status in comparison with PTA results.  
Meanwhile, SDT measures the lowest intensity at which a patient can detect the presence of speech sounds without necessarily understanding their meaning. This threshold is determined at the point where the patient simply perceives the existence of an auditory stimulus. SDT values generally exhibit a strong correlation with the lowest threshold obtained in pure-tone audiometry and tend to be lower than SRT values [14].  
[PERSON] et al. [15] conducted a study analyzing the correlation between pure-tone audiometry (PTA) and speech audiometry as a cross-validation method to enhance the accuracy of hearing assessments. The study included 52 children aged 5 to 14 years (30 males, 22 females) with hearing loss, who underwent pure-tone audiometry and speech audiometry. Statistical analyses included the Pearson correlation coefficient and the chi-squared test, with a significance level of \(p<0.05\). The results showed that the speech detection threshold (SDT) strongly correlated with the best pure-tone threshold, with the highest correlation observed in the sloping audiometric configuration (r = 0.993). Additionally, the speech recognition threshold (SRT) demonstrated a strong correlation with PTA (500-2000 Hz), PTA (500-4000 Hz), and PTA (500-1000 Hz) (r = 0.978, r = 0.91, r = 0.909, respectively), with the highest correlation at 1000 Hz (r = 0.986). The difference between SDT and SRT was \(\leq\)12 dB in most cases (\(p=0.033\)), supporting the reliability of these measures. This study confirmed the strong correlation between pure-tone audiometry and speech audiometry, highlighting the value of speech thresholds as an effective cross-check for pure-tone threshold measurements. These findings contribute to more reliable clinical evaluations of hearing loss and provide a solid foundation for improving diagnostic accuracy in audiology.  
The speech discrimination score (SDS) is also used to assess a patient's language comprehension ability at the optimal sound intensity level, where they can hear most effectively. This is a crucial reference for customizing hearing assistive device settings [16]. It plays a key role in precisely evaluating the degree and type of hearing impairment, thereby contributing to the formulation of treatment and rehabilitation plans. In particular, the speech audiometry test helps identify the listening difficulties patients experience in everyday conversations, allowing for the optimization of auditory treatment effectiveness [17].