An experimental investigation was conducted to analyse the impact of sinusoidal ridge-type roughness on the mean flow and turbulence characteristics of a developing, moderate Reynolds number, turbulent boundary layer. A streamwise sinusoidal pattern with an amplitude denoted as (A) and a wavelength (\Lambda) was imposed on the ridges while maintaining fixed the spanwise spacing between the ridges. Hot-wire anemometry was employed to measure the boundary layer downstream of the roughness array, revealing significant modifications in spectral content between configurations with aligned and sinusoidal ridge-type roughness. In line with prior studies, the presence of ridges caused a noticeable upward shift of energy and the emergence of an outer peak in the boundary layer. This phenomenon could be attributed to the creation of a secondary flow region above the roughness elements and large-scale motion in the outer portion of the boundary layer. Interestingly, configurations with sinusoidal patterns exhibited an even more pronounced upward shift of energy in the premultiplied spectra. These findings suggest that the energy in the outer region of the boundary layer is influenced not solely by the spanwise spacing of ridges but also by the waviness of the ridges, which further contributes to its intensification. Notably, the introduction of a sinusoidal pattern increased the von Kármán constant. While ridges with no waviness displayed a decrease in the log-law intercept, in line with regular roughness effects, the incorporation of sinusoidal shapes heightened the log-law intercept, underscoring its significant impact on flow characteristics. Furthermore, measurements from oil droplet interferometry revealed that the presence of ridges locally reduced skin friction. Among the configurations, those with shorter sinusoidal wavelengths exhibited the lowest values for skin friction, with, however, the increase of pressure drag likely present.