Single denture syndrome represents an example of a complex pathologic condition of the entire stomatognathic system with a variety of hard-tissue, soft-tissue, and occlusal changes. These changes, initiated by a certain sequence of events, beginning with a prolonged period of tooth loss that can lead to severe bone atrophy in different regions of the jaws and loss of masticatory function. This study was conducted on sixteen patients with signs of single denture syndrome (ten females and six males) and eight normally speaking subjects with normal dentation as a control group (group I); to investigate the effect of prosthodontic rehabilitation of single denture syndrome (mandibular implant retained removable partial overdentures versus mandibular conventional partial denture) on sound production. The patients with signs of single denture syndrome were medically fit and free from any systemic or oral abnormalities that have their effects on the speech and osseointegration. The patients with signs of single denture syndrome were divided into two groups. Group II: for each patient the maxillary complete dentures and mandibular conventional removable partial dentures were constructed. Group III: for each patient the maxillary complete dentures and implant retained removable partial overdentures were constructed. Phonetics evaluation was performed by two methods for each patient in the two groups. The records were taken immediately after denture insertion and another recording two weeks later. The speech evaluation procedures were performed as follows: Auditory perceptual assessment by the aid of two phoniatricians and three unfamiliar listeners and acoustic analysis by analyzing spectrogram resultedfrom computer speech lab (CSL). Parameters evaluated using the spectrogram included: consonants duration, average energy and formant transition for the following sounds (/ t /, /t/, /s/, /ʃ/, /l/, /r/, /g/ and/ k/) Perceptual assessment revealed significant differences between group II, group III and the control group at time of insertion with significant improvement in speech with time due to adaptation. Acoustic analysis revealed significant differences between the two denture groups and the control group regarding the consonant duration and average energy of anterior and lateral sounds but regarding the formant transition, the statistical analysis revealed insignificant differences between the two denture groups and the control group. Regarding patient’s satisfaction and phonetic outcomes; the results obtained revealed that the implant retained prosthesis group exhibits more favorable results in comparison with conventional prosthesis group.