Why in a strong acid and strong bases reaction, a drop of acid added would not change its PH dramatically but has a big drop near the equivalent point?

PH scal is a logarithmic scale which means PH 3 is10 times more concentrated in hydrogen ions then PH4. PH scale is therefore the negative of hydrogen concentration. Now When a drop of atrong acid, even if the drop has a high concentration of hydrogen ions, the concentration in the total solution is insignificant, hence the PH does not increase much. Nevertheless, near the equavalent point where most of the strong base had been neutralised by the strong acid which leaves a fairly neutralised solution at around PH 6. in this case, even a little drop of the strong acid can change the PH dramatically because the concentration of hydrogen ions in the acid has a direct impact on the excess hydrogen ion concentration of the solution without the buffering effect from the neutralising reaction.