Diaphragmatic breathing (DB) is a non-pharmacological intervention to reduce stress, anxiety, and depression. It involves the rising of the abdomen as the person inhales, the contraction of the diaphragm, and retraction of the abdomen as the person exhales. It helps in sustained attention, reducing anxiety and cortisol level. Speech is one of the easily accessible modalities of human expression and is closely involved with breathing. Speech is produced by the modulation of air to be exhaled as part of the breathing in the lungs. This work investigates the effect of DB on speech. The experiment has been performed on undergraduate students. The speech recording of students before and after DB is recorded. The emotional state of the students before and after the experiment has also been evaluated using the short-State Trait Anxiety Inventory. The speech features used for the analysis belong to the extended Geneva minimalistic acoustic parameter set (eGeMAPS). The features include frequency-related, energy-related, spectral, and temporal features. The significance of features is found using paired t-test. The significant features in the eGeMAPS show that the temporal features, amplitude features, fundamental frequency features are significantly affected due to DB.